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Encouraging News About Coronavirus Immunity

We’ve had some good news on coronavirus immunity recently – good because it gives us some more clarity on the whole situation, and because it suggests that both people who have already recovered from the infection and people who will be getting vaccinated can have good protection.

We have this preprint from several of the Boston/Cambridge area institutions, comparing antibody levels in 259 infected patients (out to 75 days post-symptoms) with 1548 pre-pandemic samples. They’re looking specifically at IgM, IgG, and IgA comparisons. IgM is the first antibody type to appear in response to an infection – they’re the ones I mentioned in this post as being five of the Y-shaped units put together. IgG are the ones that most people are talking about when they talk about antibodies in the blood, and IgA are secreted mucosal antibodies, found in the saliva and nasal/lung tissues. That mucosal immunity is surely an important factor in a disease that appears to be spread largely by inhaled airborne droplets.

They estimate that it takes about 11 days to “seroconvert” after infection, that is, to show evidence that your immune system has raised these new antibodies to the coronavirus. Looking at hospitalized individuals versus milder cases, the former actually seroconverted a couple of days earlier, and their IgM response tended to drop off a bit more quickly. One limitation of this paper is that the coronavirus patient cohort was skewed towards the hospitalized patients, rather than mild infections. But overall they found that IgG antibodies were still detectable in serum 75 days out (the last time point measured) and were a very useful marker for infection, although IgM and IgA had mostly gone back down by then. The paper concludes that although we don’t yet know the optimum levels of antibodies for protection (and we’re still collecting later time points!), “the association between RBD-IgG with neutralizing titers and the persistence of these antibodies at late time points is encouraging“.

Here’s a report on the same topic from a multicenter team in Canada that’s comparing antibody level both in the blood and in saliva.  In contrast to the report just mentioned, the authors here found IgA against the coronavirus persisting for at least three months after infection, and correlating well with IgG in the blood. Not every study has shown that sort of persistence, but the authors believe that this might be due to the techniques used for detection. They also found that several of their negative controls – samples banked from people pre-pandemic, who had definitely not been exposed to coronavirus – also showed IgA titers in saliva, presumably cross-reactive antibodies that were raised from some other infection. “It is tempting to speculate“, they write, “that these preexisting IgA antibodies may provide some stop-gap protection against SARS-CoV-2 in the oral cavity, and if so, it is essential to ascertain their original antigenic specificity.”

Then there’s this preprint from a team in Arizona, which confirms these results by finding that antibodies against the RBD part of the coronavirus Spike protein persisted for at least three months. “In contrast to other reports“, they say, “we conclude that immunity is durable for at least several months after SARS-CoV-2 infection“. They also checked antibodies to the nucleocapsid protein (N) as well as to the spike and found that the N response was more variable. One possibility they raise is that there are cross-reactive antibodies to other coronavirus N proteins (which is a more conserved domain across the various types than the Spike), and that these were raised by previous infections with different viruses.

Moving past antibodies, we have this paper on T-cell responses. The authors, a multinational team led out of the Karolinska Institute in Sweden, have put in a lot of work looking at the T-cell situation in unexposed individuals, people with acute coronavirus infections and those who have recovered, and family members of those patients as well. The acute phase subjects had just the sort of cellular profile you’d expect: highly activated and cytotoxic, out there killing virus-infected cells as T-cells were born to do. In the convalescent patients this had calmed down, as it’s supposed to, and they detected stem-memory-type cells, which is just what you’d want to see. Importantly, these were also found in people who had recovered from much milder infections and in the asymptomatic family members tested as well. (The paper provides a great deal of detail on the exact sorts of responses in the various T-cell types that I’m not going into, but it’s valuable information).

They also detected potentially cross-reactive T cells in 28% of people who had donated blood before the pandemic even hit, which is consistent with several other reports. 41% of the overall patients who were seronegative in antibody tests were still positive for T-cells (CD4+ and CD8+ alike) against coronavirus proteins (Spike, nucleocapsid, and membrane). They conclude that the T-cell response is indeed non-redundant and apparently an important part of immunity to this virus, and that using seroprevalence (antibody levels) as a marker for exposure in a population will almost certainly underestimate the real situation. That’s good news, since it would mean that more people have already been exposed (and are to some good degree immune) than we would think. But that doesn’t mean that we can blow the all-clear whistle, either, as the various surges in infection around the world have shown: the situation may be better than feared, but we don’t seem to be anywhere near “herd immunity” levels yet. And we would be killing off an awful lot more people to get there without a vaccine.

And finally, we have this report from the University of Washington, which is about as direct a measure of immune protection as we’re likely to get before the vaccine efficacy trials read out. The authors studied the crew of a fishing vessel, before and after its voyage. Three crew members showed a positive antibody response beforehand, indicating that they had been infected earlier in the epidemic – they were not positive in RT-PCR testing, though, indicating that they did not have active infections. In fact, none of the other 120 crew members tested (out of 122 total) had such a positive reading on departure.

But an outbreak occurred on the ship anyway – someone was early enough in the infection that they hadn’t shown positive yet. This crewmember became sick and the vessel returned to port on Day 18 of the voyage. (Sequencing of viral samples from a number of crew members confirmed that the outbreak seemed to originate from a single source). Testing then and over the next few days showed that 104 of the 120 crew members were now positive for the coronavirus – but not the three who had antibodies beforehand. This high attack rate (!) and apparent protection makes a strong case for protective immunity, because God knows everyone on board had plenty of chances to catch the disease.

How long this protection lasts, what part of it is due to antibody response and what part to T cells, and what the exact cutoffs are for those – these are the important things we don’t quite know yet. But the picture is becoming clearer. And what we’re seeing is that this virus, which it has definitely has some unusual features, is also something that our immune systems are dealing with in the just the way that you would hope to see. That gives us hope that the vaccines are in turn going to raise protective, lasting responses. We just have to see the details!


111 comments on “Encouraging News About Coronavirus Immunity”

  1. Sulphonamide says:

    Where do you find the time!? How many hundreds of person hours a day are you saving the world economies by doing all this work for us (well, those in academia who would otherwise have to track down and distill each article, as well as those so addicted that they cannot now refrain from reading all things Covid).

    1. Seb says:

      Yes! Derek Lowe is doing an amazing job, reporting the way he does.

      1. Oudeis says:

        And yet I get grumpy when he goes a few days between posts. Who says you need to pay for something in order to feel entitled to it?

    2. Pat A says:

      I subscribed to Science Mag during the pandemic solely because of Derek’s work

    3. An Old Chemist says:

      I am sure that Derek does not write all the posts himself because the posts on this blog cover diverse subjects, from synthetic organic chemistry to pharmacology to immunology to process chemistry to development to outsourcing to marketing and finally to cooking Thanksgiving Turkey and Iranian Pulao. I would guess that Derek has got a staff of a few people whom he makes work tirelessly (a necessary skill that he learned while doing his Ph. D. at Duke). Anyway, who cares? I have been reading this blog every morning now for about twenty years, and so, Derek, thanks to your staff for covering all the posts so well- concise, timely, and educational.

      1. Derek Lowe says:

        Hah! Nope, it’s all me. I’m a wordy guy, and I type quickly.

        1. Riah says:

          Do you ever sleep?

          This is such fantastic positive info, thanks so much!

        2. SJ Chapman says:

          Isaac Asimov wrote: “In a review of one of my books … I was described as: “Once a Boston biochemist, now label and linchpin of a New York corporate authorship-”

          He went on to refute that claim. And he still somehow found time to answer my elementary questions (about isomers, if you’re wondering), by postal mail, in the early 1970s.

          Was he in fact a robot? Only Dr. Susan Calvin could ever tell 😉

    4. Alex says:

      I lurk here but would like to concur. Excellent job and service even though I’m no scientist. Very useful and important information free from all the politics and noise.

      1. Agreed the comparative vaccine & immunity analyses are indeed a public service and appreciated.

  2. David G. Whiteis says:

    This is a question about the concept of vaccine “effectiveness” and how it interacts with already-existing immunity. Not being a statistician, I’ll try to word it as coherently as possible.

    As we know, there’s a growing tide of opinion suggesting that asymptomatic carriers, and probably at least some people with mild symptoms, may well have partial immunity, although the precise mechanism of how this has developed remains unclear. So, my question, which again I hope I’m wording coherently: The projected “effectiveness” of a vaccine assumes NO immunity in any of the people who receive it, right? But if a significant percent of the people already have partial immunity, does this mean that in effect they are “part way there,” so to speak, so a vaccine might have greater than anticipated effectiveness on them?

    Thus, a vaccine that was supposedly 50% effective, might actually turn out to be (let’s say) 70% or 75% effective for those who already had partial immunity — and these data, in turn, would improve the vaccine’s overall effectiveness rate across the population.

    Then, at least in theory, perhaps a projected less-than-optimal vaccine effectiveness, along with the feared less-than-optimal rates of uptake across the population, might not impair our eventual arrival at some semblance of herd immunity as originally thought?

    It’s clear that “herd immunity” is not a 0/1 binary; it seems to be becoming more clear that individual immunity may not be, either. Might this be good news in terms of vaccine effectiveness in helping us reach some semblance of herd immunity more rapidly and efficiently than originally thought? Or am I grasping at straws (“spikes”?) here? . . .

    1. Dr McGill says:

      If preexisting immunity exists in both the treatment and placebo groups, I believe results of vaccine efficacy would be understated. The placebo group would have a higher than expected immunity compared with the treatment group. If pre-screening for (e.g., T-cell) cross reactivity was performed, this bias could be eliminated.

    2. Riah says:

      It could also equally work the other way -interfere with natural immunity. And there is potential for ADE still

    3. x says:

      You’re asking about interactions which are far too complex and situational to draw general conclusions about. No, you can’t just add A to B to get C.

  3. steve says:

    There are four coronaviruses that circulate every year and are responsible for ~20-30% of what call “colds”. We NEVER develop herd immunity to these even though they’ve been around forever. In challenge experiments, immunity to these was transient as it is with SARS-CoV-2. It may be that one or more vaccines will give long-lasting immunity (a year or more) by epitope direction but the history of these viruses suggest that any immunity will be short-lived and that only annual vaccinations will provide adequate protection.

    1. Walter Sobchak says:

      Ok, they will add it to my annual flu shot.

    2. Robert Williams says:

      We never become immune to colds, or to the current mutation thereof. However, importantly, colds do not kill us. It is Covid’s novelty that makes it uniquely problematic. If we can reach the point where Covid mortality and morbidity are the same as the common cold or seasonal flu, that looks an awful lot like success.

      1. David G Whiteis says:

        Not necessarily, according to some public healthy policymakers. Allison Arwady, director of Chicago’s Department of Public Health, is holding for for a vaccine that’s “100% effective” before she’ll consider openning things up fully, relaxing “distancing” and masking mandates, etc. A reduced symptomology won’t be enough — she spefically stated that it will not be sufficient if ” . . . people who are vaccinated might still get COVID-19, but the vaccine could ensure their symptoms aren’t as bad.”

        She’s going to wait for NO new cases, regardless of severity, “over a sustained period of time.”

        Looks as if we’ll be spending most of the rest of our lives shunning other peole, quite literally like tha plague, and not seeing anyone’s faces; nd our children will grow up never being able to hug a friend or share a smile with a classmate. Festivals? Clubs? Live music/arts/ theater? Not a chance. Feeling free, unafraid, and at ease in the company of strangers (or even close friends and loved ones) at close proximity? Ditto.

        1. Kerry says:

          Do you have a link to these specific comments? I have not seen her discuss this so explicitly

          1. Thomas says:

            She probably doesn’t want to give up on all measures when the first batch of vaccines is delivered.
            And there is the choice – either vaccinate the complete population with a 100% effective vaccine. Or vaccinate enough people that cases subside even without measures.
            So in a way the words make sense, though they likely have been taken out of conext just a little bit.

          2. David G Whiteis says:

            There have been several news releases over the last few weeks — I don’t remember now where I got this particular quote; I’ve been following it prettty closely, and I’ve seen articles in the Tribune and the Sun-Times, as well as other local news outlets (print, online, and TV).

          3. Dyna says:

            Seems an exaggeration as you’d expect, a quote I found was

            “Masks are going to be with us for some time, even after a vaccine is available,” she said. “It’s going to be at least a year to get that vaccine to everyone, and during that time period, we’re going to need to protect each other.”

          4. David G Whiteis says:

            Okay., many thanks — it’s difficult to parse and track down the context of quotes in news stories, and I’ll be the first to admit it if I got sometihing wrong or was sideswiped by an out-of-context quote (or headline). Whether “at least a year” is an accurate projection (others have suggsted “by late 2021, which would probably be more like somewhere between eight to ten months, if we go by the current projections of when a vaccine would be widely available), that’s a lot more specific than the reference I found.

            Thanks again.

          5. David G Whiteis says:

            . . . and again I apologize for the double quote, but if you can find the New York Times article from August 14, “These Fun Activities Are Likely to Become Things of the Past,” you’ll be able to see what I mean.

            Future looks bleak, folks.

        2. x says:

          “Looks as if we’ll be spending most of the rest of our lives shunning other peole, quite literally like tha plague, and not seeing anyone’s faces; nd our children will grow up never being able to hug a friend or share a smile with a classmate. Festivals? Clubs? Live music/arts/ theater? Not a chance. Feeling free, unafraid, and at ease in the company of strangers (or even close friends and loved ones) at close proximity? Ditto.”

          No one had much problem with that sort of thing when it only affected a smaller segment of the population, and I’m sure no one will have a problem with it again after COVID-19 passes into history in a couple years.

          1. David G Whiteis says:

            Perhaps, but remember — back when it only affected a small portion of the population, few people understood its virulance and its seriousness. Most folks weren’t afraid of it at all. Now they are. This fear may well be the driving factor behind most/all social and cultural behavior and relations from here on out.

          2. David G Whiteis says:

            . . . and again I apologize for the double quote, but if you can find the New York Times article from August 14, “These Fun Activities Are Likely to Become Things of the Past,” you’ll be able to see what I mean.

            Future looks bleak, folks.

  4. Carl says:

    This is very encouraging news. And, I’d like to say thank you for this blog. It’s a wonderful resource for a layman like myself who is trying to understand the critical virology news of the day.

  5. David G. Whiteis says:

    Speaking just for myself, the idea of an annual booster shot isn’t intimidating at all (a lot of us have been doing that with flu shots for years). If COVID could be kept at bay for most people through an annual booster, and then if we had an effective therapeutic that might significantly reduce symptoms for those who would still contract it, would that not suffice?

  6. Frank Kushner says:

    Bet ya there will be no vaccine for a cold type sars virus. So concentrate on surviving and prevention using quercetin, vitamins C & D and of course zinc. If you have symptoms they now say that “usually” come in this order fever, cough, body pain, nausea. This fall especially get flu check right away (hopefuuly school nurses can be allowed to as well as new Yale spit test) and get prescription for z-pack whether it’s that or Wuhan virus, then triple the dose of those great natural meds if not allowed to have hydroxycloroquine for Covid.
    See Dr Zelenko’s twitter feed @ zev_dr – remove space

    1. An Old Chemist says:

      ……..and pray to God to protect you because now smart-head Derek has professed that “This high attack rate (!) and apparent protection makes a strong case for protective immunity, because God knows everyone on board had plenty of chances to catch the disease.”

    2. Driiiving, k thx bye says:

      Probably troll, but it’s hard to tell.

    3. Guadalupe Franco says:

      I totally agree with you Frank Kushner.
      We should concentrate on strengthening out immune system. None talks about this form of prevention, I wonder WHY?
      This would diminish the anxiety of the fear that is the real and devastating disease we are into.
      To have a truly safe vaccine, particularly the ones based on inyecting genetic material such as mRNA or DNA made in the lab or from animal sources, as most of the vaccines under development, strictly they should be monitored for years to really know the effects on our DNA, that could get modified for life.

      Gene therapies being developed for other chronic degenerative diseases have been on trials for years and years and most are still not approved by FDA. How in the world a vaccine developed in few months or a year, will get through it? I wonder WHY?
      Many questions arise in my mind, some with no answers, and some with answers I am reluctant to hear or accept.
      God bless us all. 🙏🌺

  7. N says:

    Derek, could you envision a clinical test where someone with cross-reactive T-cells, who suffered mild-to-nil symptoms with Covid, yet didn’t get tested with PCR or for antibodies in the appropriate timeframe, could _ever_ know if they did/did not have Covid-19?

    1. x says:

      I can’t, off the top of my head, and I work in the field (albeit as a bench grunt). But why would you even need to know?

  8. nobody says:

    With such a high attack rate in confined spaces, we’d need near universal vaccination, with a nearly 100% effective vaccine, for group activities to have an acceptably low risk to participants and an acceptably low risk of overloading local healthcare systems.

    A 70% effective vaccine only gets you a fishing boat with 30 infected people (six of whom will likely require hospital care) rather than 100, and that’s still a fishing boat that has to turn back.

    There’s no ‘back to normal’ from this.

    1. Bryon Wasserman says:

      A vaccine that is 70 percent effective that blocks infection/transmission* means that we can suppress the virus while going back to normal life. Conditions that would give us an R of 1.50 give us an R of .75 and the virus becomes extremely rare after a few months. The people on the ship won’t universally be protected but they have a much lower chance of getting it.

      *unclear whether the vaccine will do this, but this is the hope.

      1. nobody says:

        So much of the SARS-CoV-2 spread is driven by super-spreading events that my concern is that it will not be possible to control the virus without measures that can prevent super-spreading events. That’s not going to be possible without combining vaccine with physical distancing measures on a long-term basis.

        A low population-wide R doesn’t mean much if the “R” in confined spaces can hit 100. Unless the virus is completely eradicated, indoor gatherings are still a potential death sentence even if a vaccine reduces the confined spaces “R” to a mere 30.

        1. Harald says:

          But that would still be tolerable if the probability of someone being infected to spread it in the first place was low enough. Especially if the vaccines can lower the risk of a severe course of the disease.
          You’d still get outbreaks here and there, but no uncontrolled spread.

          1. David G Whiteis says:

            Yes — isn’t that the case with yellow fever and other highly contagious diseases that have been successfully controlled but have not been entirely eradicated? If “total” eradiction were the only answer, we’d still be distancing and masking ourselves all over the world to prevent virtually everything but smallpox.

        2. x says:

          The R in a confined space with 100 uninfected people is 0.

    2. Michael says:

      You’re assuming that by the time a vaccine has been not only developed but distributed to everyone on a fishing crew, there have been no therapeutic advances keeping infected people, no diagnostic advances allowing point-of-care assessments of infection, and — despite universal vaccination — no herd immunity breaking the chain of explosive epidemic growth.

      Your pessimistic scenario does not have a realistic sense of the order of events to come.

    3. confused says:

      “overloading local healthcare systems” is definitely not happening with an even partially effective vaccine. It really hasn’t happened nearly as much as was predicted earlier in the pandemic, given the pretty limited measures taken in much of the southern/western US. Sure, there were some cases of patients being transferred to hospitals in different parts of the same state, but systems overall have coped well.

      As for acceptability of risk… a lot of things are going to reduce the risk. If COVID is (say) 8 times worse than flu now, and a vaccine reduces that by 75% (3/4), and better treatments cut the risk in half … well that comes out the same. And it could easily be much better than that.

      In 2009 I was in college (Texas A&M), and we went on with classes as normal as H1N1 spread through the campus. They put out hand sanitizer in common areas and sent out warnings, but not much else. (I got it, but a mild case.)

      1. David G Whiteis says:

        False analogy, I fear. R0 for N1H1 was about 1.46. For COVID, it’s between 2 and 2.5. N1H1 mortality rate was 0.02% (perhaps because it primarily affected children and young adults, whose immune systems tend to be stronger). For COVID, it’s closer to 2% (and counting, I believe).

        1. David G Whiteis says:

          That being said, though, I am rather miffed at the so-called “mainstream” news media, with the way they continue to obsess with vaccine reports that really don’t tell us anything except that the trials are ongoing — while virtually ignoring what could be very encouraging, even game-changing, news about therapeutics and treatments. (Or are we assuming that therapeutics will only be available and administered, probably in hospitals, to people with extremely serious symptoms, not the general population of mildly / asymptomatic congagion spreaders, who are the real culprits in this disease’s spread?)

          I also wish that people making projections about the possible effectiveness of vaccines in helping us return to “normal” (whatever that is) would also include therapuetics in their calculations. (LAM-002A is one that seems very encouraging, although reporting on it has been so scanty that I really can’t say for sure.) Even Dr. Fauci, as much as I admire and respect him, seems dedicatd to pursuing a “vaccine or nothing” approach in terms of envisioning a medical solution to this problem.

          1. WetDog says:

            Hope is not a plan. We have had limited success in ‘cures’ for viruses. We have had a long and successful history of creating effective vaccines for same. Makes sense to push on that lever.

            The mainstream media *has* reported on the various treatment improvements that we have seen over the past couple of months. Ventilation strategy improvements. Dexamethasone. Hydroxychloroquine (well can’t win them all), plasmapheresis and plasma transfusions.

            There are a number of other potential treatments that Derek has outlined here. Monoclonal antibodies, Interferons and interferon antagonists. But we’ve not seen much in the way of results yet. Once they’re reported, I am sure we will see reportage.

            What sources of information have you been using to get this rather skewed version of reality?

        2. confused says:

          I’m not talking about what COVID is like *now* but what it will be once we have better treatments and a majority of the population are vaccinated (or maybe 25% naturally immune and 40%-50% vaccinated…)

          Also, whole-population IFRs for H1N1 and COVID aren’t comparable for the sort of situations I’m talking about (ship crews, workplaces, colleges, etc.) — these situations don’t reflect the whole population’s age profile. H1N1 affected the elderly less; COVID dramatically more.

          You’d have to compare the IFR for say the 18-25 age group (for colleges) or maybe 18-65 (for workplaces).

          This gives a drastically different picture.

          And I don’t think COVID IFR can be 2%. That seems too high even for NYC in March/April (20-25% infected from serology, so something like 2 million… NYC didn’t see 40,000 deaths).

          It was probably a bit over 1% in early hotspots like New York and Lombardy, but not now, with a somewhat younger population (fewer nursing home patients)

          And if it’s 0.65%, Texas is doing a surprisingly good job of finding cases given our positivity rate… I’d think it’s probably lower than that for the current South/Southwest summer outbreak. (Though TX does have a very low median age for the US).

          1. Barry says:

            SARS Covid19 ain’t measles (R0=17), which seems to infect everyone who is exposed (unless they’re immune). What we’ve seen is that this one infects people (doctors, nurses, grocery clerks, sailors…) who get exposed heavily and repeatedly. ‘R’ is sensitive to our behavior (masking, distancing, washing)

    4. Bill says:

      How many people on the fishing boat actually needed hospital care? Does anybody know? It would be interesting to hear.

      It is not remotely the case that 20% of people infected with COVID require hospital care. Without question it is less than 5%; it could be more like 1%. We’re not sure what the actual infection rate is.

      1. Barry says:

        But the severity of the infection seems to correlate positively with the magnitude of the exposure. Working hard/breathing hard/shouting in the noisy crowded work environment of a fishing boat, these guys might have taken on much larger viral burdens than just sharing some other work environment.

    5. chemist says:

      Overall survival rate per CDC data is 99.96% – I think we’ll be fine. You can stop clutching your pearls. I caught coronavirus and had a fever for a few days that went away on its own. I didn’t infect anyone else either.

  9. David G Whiteis says:

    Also, “immunity” isn’t a zero-sum game. If, in fact, a vaccine might also have a therapeutic effect — reducing the severity of symtoms in people who do still contract the disease — then the scenario might not be quite so dire. Add to this an effective therapeutic to reduce the probablility of severe symptoms even further, and one would hope that there is still cause for some optimism.

    Speaknig as a non-statistician, I concur with Bryon W.’s thinking (although, isn’t his R0 estimate a little low? I thought the R0 for COVID was closer to 2 -2.5) — nonetheless, as R0 lowers, the rate of transmission should go down (i.e., the odds of running into an infected person and getting infected diminish), especially if, as postulated, not only previoulsy infected people but asymptomatic carriers and some with mild symptoms may also already have partial immunity. Obviously, this will take longer in areas that were spiking already when the vaccine got introduced (I’m talking to YOU, Florida, Georgia, Texas, et al. — get those masks on to make it easier for the vaccine to do its job when it gets here!!!)

    And although I certainly look forward to the day when masking and “distancing” aren’t mandatory (and as a lover of live music, theater, and other public performances / gatherings, — let alone one who loves to smile at people and have them smile back! — I look forward to that day even more), I think it’s also safe to say that people who consider themselves especially vulnerable and at-risk will continue to “mask up,” especially during flu season. Ditto for people who have cold or flu symptoms — just as people now cough and sneeze into their arms instead of their hands, using PPE when one is at risk of either contracting or spreading contagion will become part of a “new normal” that we can all live with.

    1. confused says:

      >>Obviously, this will take longer in areas that were spiking already when the vaccine got introduced (I’m talking to YOU, Florida, Georgia, Texas, et al

      I don’t think those places will be spiking by the time a vaccine is introduced. TX seems to be post-peak already.

  10. Marko says:

    “…They conclude that the T-cell response is indeed non-redundant and apparently an important part of immunity to this virus, and that using seroprevalence (antibody levels) as a marker for exposure in a population will almost certainly underestimate the real situation. That’s good news, since it would mean that more people have already been exposed (and are to some good degree immune) than we would think. ”

    We need an easy test for T-cell immunity that can be done in parallel with antibody surveys to get a better handle on the state of immunity in the population. This seems like the closest thing to such a test :

    The fishing boat study could indicate what the upper bound might be on the level of protective T-cell ( or other ) immunity in the population that is missed by current antibody serosurveys. If you take out the 3 sailors who showed clear evidence of prior infection upon boarding the ship , 104 of the remaining 119 sailors went on to become PCR+ , an 87% attack rate. That leaves a maximum of 13% who may have been protected from infection by some kind of immunity that was missed by the boarding serosurvey. Even if you assume the full 13% were indeed protected against infection , the question remains whether it was due to previous exposure to Cov2 or to pre-existing immunity to other coronaviruses.

    It’s a shame they were unable to do T-cell assays, because otherwise they did a fantastic job with the testing they performed on that crew.

  11. Daniel Barkalow says:

    The sort of challenge test I could see being useful new information is for those 3 people who didn’t get sick on that boat to be inoculated (again) and then try to culture coronavirus out of their breath for the next week. It’s clear that they are safe from getting sick now, but we know very little about whether they could become infectious, and that has implications for whether we should prioritize vaccinating people with a low risk of complications who interact with large numbers of people or whether that wouldn’t significantly prevent outbreaks anyway.

  12. Gonier says:

    The vaccines are being tested in adults, not children. May help with colleges, but would have little impact on elementary through high school students returning to school as the vaccine wouldn’t be approved for that target population.

    1. David G. Whiteis says:

      . . . also, what does this mean in terms of the estimates concerning vaccine effectiveness, uptake rates, the necessary number of people who need to be vaccinated in order for more widespread immunity to begin to develop, etc.? Children constitute approximately 27% of the world’s population (closer to 20% in the U.S., I believe). How does this fit into the epidemiological estimates we’ve all been seeing in terms of things like vaccine efficiency and potential herd immunity? Has everyone been ignoring anywhere from 20-30% of the population in their estimates?

  13. David G Whiteis says:

    . . . of course all of these estimates assume, if not “universal” uptake, significantly higher uptake rates than the 50 -65% estimates we’ve been getting from the U.K., the U.S., et al.

    The greatest tragedy would be if we ended up with millions of vials of vaccines sitting unused on the shelves while equivalent millions of people continued to contract the virus, and the rest of the world continued to stumble and struggle in “COVID Purgatory” with no end in sight.

    1. Duncan says:

      That is the risk that really worries me too. I guess that we will have those that refuse to take the vaccine for whatever reason and that we’ll just have to live with it. That’s not new. There are things that can be done to maximise take up – pay people to take the vaccine perhaps? It might be cheaper than another stimulus. But I don’t realistically see how vaccination could ever be more than strongly encouraged.

      But what I think would not be acceptable is stockpiling vaccines whilst elsewhere in the world needs them. I do not believe that giving first access to vaccines to the taxpayers who funded research is unacceptable vaccine nationalism. What is not acceptable however is stockpiling for the sake of it and that will be a much more divisive question. And it may be a political one if the countries in need are not on good terms with those countries that have the stockpile. For all the talk of vaccine nationalism the talk of vaccine international relations has been less discussed. Would it be right for example to tie vaccine access to steps to reduce illegal migration? From that perspective I can fully understand why states want their own domestically produced covid vaccine even if it lacks the efficiency of a truly international approach.

      I think you are right and the world at large must see a covid vaccine (assuming we get one) as a global public good. But I don’t think anyone yet has a clear idea of what that means or looks like.

      1. David G Whiteis says:

        It’s possible that as the first “phases” of vaccination progress — front-line heath care providers and other essential workers, then perhaps elderly and/or other high-risk people, as well as people in other parts of the world — the doubters will see that there’s less to fear from a vaccine than from its alternative. Rememer, most of those polls that allegedly show so few people willing to take a vaccine include significant numbers of “undecideds,” who could potetntially change their minds in the right direction — the absolute “no” answers are fewer than the absolute “yeses.” It’s the “I don’t know yet” folks that we need to work on convincing.

        1. David G Whiteis says:

          RE: Paying people to get vaccinated (not as crazy as it sounds??)

        2. Duncan says:

          My take, for what it’s worth. I suspect that in some of the arguments about vaccination there is more than a little internet braggadocio going on. I try not to take the internet too seriously, I encourage others to do likewise. Regardless there is clearly some level of vaccine scepticism, albeit for a range of reasons.

          I do not find very compelling arguments along the line that vaccines developed under the Trump administration are inherently not to be trusted. Any president of any party would have put in place some sort of fast-track vaccine programme. Indeed China (where the electoral pressure is less) and other countries around the world have put in place fast-track vaccine programmes. To that extent I don’t even see OWS as particularly radical in context and any president would have faced similar dilemmas and likely set up some sort of OWS. Indeed both the Chinese and Russians have moved faster to limited approval than has the Trump administration.

          Now I am not from the US, and I make no political point, ultimately it is for the citizens of the US to work out for themselves how they relate to presidential government and reconcile themselves to the holder of that office. It’s not my fight.

          However what is happening is that in a social media age what we have is not ‘news’ in the classic sense, rather a 24 hour always on propaganda machine about current affairs. What I think is not reasonable is for people to dismiss the vaccine for covid (or any other illness) simply on the basis of a globalised, social media-driven bunfight. There is nothing at all wrong with caution about a vaccine and equally there is nothing wrong with wanting to see good peer-reviewed data or taking advice from a trusted medical professional. [Indeed as an aside here the unquestioned rise of the pre-print has been an under-remarked upon thing.]

          What in my mind is less understandable is vaccine refusal to make some sort of culture war point. It is partly for this reason that I do not like to see science and scientists becoming embroiled in social media. Vaccine refusal if it happens should be for the right reasons and after serious and disinterested consideration of the facts. So compulsory vaccination – no. But refusing vaccination to make a political point – also no.

          What I think we as a world will need is some mechanism to cut through the culture wars and that is going to be easier to say than to do. I’ll likely be in the queue with my sleeve rolled up – but before I do that I will be doing a bit of due diligence.

        3. James Millar says:

          I hope the undecided population will be more convinced by good news than they will by the lies that will inevitably emerge – probably already waiting to launch.

        4. confused says:

          Yeah, I’m not sure how much weight to put on those surveys… what people actually do will depend on the situation at the time they are asked to make that choice.

          I would expect that e.g. healthcare workers would get it before mass distribution to the public; if that goes well, that might reduce perceived risk.

          Since I don’t expect mass distribution before November (even if there *is* an approval in October), the political situation might also look quite different.

          (And yes, I know the administration doesn’t actually change until January, but the results of the election will still strongly impact public perception & the media/social media atmosphere.)

      2. David G Whiteis says:

        I’m guessing that some governments will simply make vaccination mandatory. Short of that, once a vaccine has been approved and made widely available, employers can, and should, require proof of vaccination among their employees, at least in cases where this is practicable. I think school systems should do the same with students (assuming, of course, that said vaccine is truly available and accessible to all communities — no child should have to be penalized because of where his or her parents live).

        I might also suggest that in the absence of a governmental mandate (which apparently would be Constitutional, but would be politically infeasible in the U.S.), at least some private entities — restaurants, bars, performance/entertainment venues such as nightclubs, show lounges, auditoriums, gambling casinos, etc. — could have an impact by mandating that proof of vaccination would be required for entry (not unlike having show an ID to purchase alcohol). It might mean fewer patrons for a while, but it couldn’t be much fewer than the current “25% – 50% capacity” restrictions that a lot of places are being held to right now — and, in the long run, it would attract more patrons who otherwise might not feel safe going out.

        It would also, one hopes, encourage vaccine “fence-sitters” to get vaccinated, just so they can join the fun. I’m sure there are plenty of other people like me, so hungry for normal human contact again that we would revel in the opportunity to gather safely together with other “vaxxers” in normal social settings. Let the vaxxers be the “in-group,” and the anti-vaxxers be the “other.” In other words, a “carrot” approach rather than a “stick” approach might be the most feasible,and the most likely to produce good results. It’s possible, also, that this could lead to a kind of positive, proactive social “shaming” of people who refused vaccination (I could actually envision “Vax Parties” springing up around the country, making it “cool” to be vaccinated.)

        Creative thinking will be essential in helping bring about a situation in which we can return to a post-COVID “normal.”

        1. chemist says:

          Why the hell should my employer force me to take a vaccine for a disease that has a 99.96% survival rate (and near 100% in non-susceptible populations)? Has the world just become completely pussified?

          1. David G Whiteis says:

            “Why the hell should my employer force me to take a vaccine for a disease that has a 99.96% survival rate (and near 100% in non-susceptible populations)?”

            Maybe because (1) COVD-19 has an R0 of somewhere between 2 and 3, which means that if you have it, you’re likely to infect several other people, each of whom is likely to do the same, etc. etc. etc. — and at least some of those people will be decidedly NOT “non-susceptible” (over 80 percent of COVID-19 deaths occur in people aged 65 and older — know anyone like that?); (2) hence, widespread vaccination is the only way we’ll be able to stem the tide of catastrophic situations like we’re seeing in Florida, (over 10,000 deaths, 119 new ones in the past 24 hours), Georgia, (4,899 deaths, 55 new), and Mississippi (2,214 deaths) — just for starters — as well as in countries like Peru (27,034 deaths) and India (54,849 deaths, 983 new) — or, for that matter, the U.S. overall (175,000 deaths and counting); and (3) public health is a public good, we’re all in this together, it’s not all about “ME”.

        2. chemist says:

          My body, my choice. I will refuse a vaccine for a disease that has a 99.96% survival rate.

          1. Barry says:

            The Supreme Court of the United States weighed this a hundred years ago (‘Jacobson v. Massachusetts’) and found that the govt has a controlling interest in the Public Health. You can be imprisoned for refusing vaccination or otherwise imperiling the Public Health (see “Typhoid Mary”)

          2. chemist says:

            “You can be imprisoned for refusing vaccination or otherwise imperiling the Public Health.”
            For a disease with a 99.96% survival rate huh? Whoever tries throwing me in jail for that is going to be the person who ends up in a grave.

          3. Kaleberg says:

            Just stay where you won’t infect someone else. Even devout gun rights sorts accept some restraints on where people can point and fire.

          4. Amanda says:

            Death isn’t the only bad outcome. We’re only beginning to know the morbidity associated with COVID. As we are learning more, this is likely a bigger public health crisis than just the deaths are showing us. Besides, even that “small” percentage of deaths is a lot of real people with families. Those deaths would also lead to public health and economic consequences.

  14. David G Whiteis says:

    Late-breaking news (CNN, if I’m not mistaken) — ” . . . 44 percent of Republicans believe the debunked theory that [Bill] Gates is promoting a COVID-19 vaccine campaign in an effort to implant microchips into people’s brains to track their movements. Nearly 20 percent of Democrats said they believed the theory.”

    Whatever optimism I began with is rapidly fading away . . .

    1. Marko says:

      Why would Gates , or anyone , need to implant chips to track people’s movements ? People already carry tracking devices voluntarily , almost universally. They’re called cell phones.

    2. Unconvinced says:

      The amazing thing here is the number of people who think they are worth microchipping.

      1. John Wayne says:

        Agreed. You can learn more about somebody from their online activity than their GPS location.

        1. Hap says:

          Particularly now. “Yep, they’re still at home, on the computer…”

    3. Driiiving says:

      Are you sure you want to take everything on television is gospel?
      Media lives on sensationalism. If they did a survey and the numbers came out 12 and 6%, do you think they’d make a news clip of it?

      1. David G Whiteis says:

        Well, it’s certainly true that the surveys vary widely. Here’s one that says virtually the opposite of what most of them say, concerning Americans’ willingness to be vaccinated. It would seem that the old cliche that “it’s all about how you ask the question” (and how you massage the data) still holds:

  15. Toni says:

    an interesting hypothesis of the group around Emmanuelle Charpentier.
    Hypothesis: RNA and DNA Viral Sequence Integration into the Mammalian Host Genome Supports Long-Term B Cell and T Cell Adaptive Immunity

  16. Barry says:

    That you can find cross-reactive IgA in old samples from before the pandemic is interesting. But the epidemiology does not point to heterologous immunity as a big factor in this one. If that were controlling, we’d see less infection in older individuals who had immune memory of more coronaviruses past (like the 1918 flu spared subjects over 50 yo) and more infection in younger subjects (who lacked such immune memory). Instead, what we’ve seen in the U.S. (SE Asia may be different?) is the greatest disease burden on the front line (physicians, nurses, respiratory therapists, grocery clerks, choir members…) where exposure is greatest. Something else (innate immunity?) also protects young children from this one.

  17. DTX says:

    Can someone explain why “history of these viruses suggest that any immunity will be short-lived” (Steve’s point).

    We need a yearly flu vaccine because the virus constantly mutates. What it is about coronaviruses that causes the immune system to “forget them” so rapidly? Why is immunity to these viruses short-lived?

    As other have noted, I can’t thank Derek enough for this blog. I can imagine why he would invest time in this blog because his contribution is so valuable.

    1. Barry says:

      While this novel Coronavirus is novel (duuh!), we have studied related viruses and immune response to them. Immunity to MERS persists for years, at least

    2. Riah says:

      As far as I can see from wading through dozens of papers, there is enough research to strongly suggest immunity to SARS-CoV-2 is very long lived (as it is to SARS-CoV-1). There is only flimsy reasoning (serum antibodies waning, which is pretty meaningless as plasma/ memory B are still generated) and supposed lack of immunity to cold coronaviruses (contentious at best) to even suppose otherwise.
      That’s unless it undergoes several mutations rendering it unrecognizeable to all the dozens of different epitope recognizing T-cells. Which is unlikely. Many immunologists also believe this is the case.

      1. Coronaviruses actually have a built-in repair mechanism that repairs mutations. They generally don’t mutate as much as Orthomyxoviridae.

  18. Grebs says:

    From the fishing boat study:

    Interesting results however:

    “ This study is limited by lack of information on clinical symptoms”

    You don’t say, authors. Im just going to assume it didn’t turn out like the Mary celeste. I think this paper shows that its very likely everyone on the diamond princess was exposed.

    1. Marko says:

      Similarly , repeat infections are being reported in NYC Orthodox communities :

      At this point , I think there’s been enough such cases reported to suggest that it’s a real phenomenon. The question remains as to whether it matters a great deal over the long haul. If a primary infection , or a vaccination , reduces the impact of a subsequent infection to something akin to a common cold , we’ll still be OK once everyone has either been infected once or vaccinated effectively.

      My not-too-ambitious ( I hope ) goal for a Cov2 vaccine is that it changes Cov2 into the fifth known common cold coronavirus.

      1. David G Whiteis says:

        ” If a primary infection . . . reduces the impact of a subsequent infection to something akin to a common cold , we’ll still be OK once everyone has either been infected once or vaccinated effectively.”
        Is there any evidence that this is the case? Most reporting on “new cases” seems to be rather vague about these cases’ severity. Do we have any data indicating that these “repeat” infections are, in fact, less serious? Or is it too early to tell?

        1. Marko says:

          I don’t think there’s been a sufficient quantity of confirmed repeat infections to say much about the relative severity of disease to be expected in such cases. As time passes , I expect we’ll see some studies that address this. The expectation at this point is the same as that for vaccines , that if they don’t 100% protect against infection , they’ll at least provide some protection against severe disease. We just don’t know for sure yet.

      2. David G Whiteis says:

        (Sorry about the multiple posts) —

        RE: “My not-too-ambitious ( I hope ) goal for a Cov2 vaccine is that it changes Cov2 into the fifth known common cold coronavirus.”

        The argument I’ve seen against this is that it would basically create a new population of asymptomatic or mildly symptomatic carriers, still capable of sparking new outbreaks among the non-vaccinated, or those for whom the vaccine is insufficiently protective. Some policy analysts, in fact, have suggested that a vaccine that offers anything short of sterile immunity should not be approved, for this reason.

  19. Oudeis says:

    I’m curious: how do these antibody and T-cell numbers compare to the numbers for other viruses after similar periods of time?

    We obviously can’t know for certain whether COVID-19 immunity lasts five years until five years after people started catching COVID-19. But it seems like it might be interesting to know whether particular immune responses are dropping off faster or slower than they do for viruses we know more about.

  20. matt says:

    This is a bit off this topic, and perhaps a little premature except to start thinking about, but what will humanity have gained from the enormous money and effort addressing coronavirus? And what _should_ we be learning or gaining but need to be deliberate about making sure it happens?

    For the first, seems like we may gain a few new vaccine routes, including some that might offer more rapid response times. And surely a lot more (vaccine, antibody, RNA) production capacity, though whether that is durable or repurposable, I don’t know. We may gain a few more insights into the balances between types of antibodies and T-cells, maybe some age-related differences in immune response (might be useful in the longevity research). We certainly have seen more mask research, from a vastly more diverse perspective. We may have inadvertently learned more about the need for cod liver oil or vick’s vaporrubs or hot toddies or (modern) tonic water plus zinc pacifiers, not for the body, but to calm the over-excited minds which otherwise are going to produce quack cures and conspiracy theories.

    For the second, a redundant, urgent, supervised rapid ramp-up of testing. A renewed commitment (I hope) to properly executing the epidemiologist’s playbook. A renewed effort for community buy-in for public health measures. Perhaps recognition of a need for a broader infrastructure for doing (proper) clinical trials in the US, rather than just ad hoc, meager, one-system retrospectives because timely, well-powered prospective RCTs seem out of reach. Thoughtful consideration of supply chain diversity, disruption resistance, and surge capacity. Related, the national stockpile, its replenishment and disbursal methods.

    Lots of other things too, right?

    1. Barry says:

      We may learn a lot about novel vaccine modalities, and we may finally learn to vaccinate against TB. The old BCG vaccine elicits titers of IgG in the plasma compartment and protects against miliary TB, but fails utterly to protect against infection on the surface of the respiratory tract (the major route of TB infection).
      If when someone comes through with a SARSCovid19 vaccine that elicits protective immunity on the respiratory mucosa, we’ll have to revisit tuberculosis. That’s a vaccine problem that has defied us for a hundred years.

  21. Erik Dienemann says:

    Derek – another great article, thanks! Slightly surprised, though, that you didn’t mention the Krammer paper (Mt. Sinai) showing ~20K convalescent patients with durable antibody response three months after recovery or the somewhat similar Chinese study showing this ~6 months later, given their earlier outbreak.

    As an aside, with regard to the T-cell response in unexposed people, I wonder if it’s possible to do a retrospective study of pre-COVID blood donors and evaluate whether the ones with highly active T-cells for CV2 had different outcomes wrt/CV2 (getting it, severity, death, etc.) vs. those with no apparent T-cell cross-reactivity? That might answer the question of the extent of existing immunity, at least epidemiologically, especially if the sample sizes were large enough to ensure a decent percent in each group had been exposed.

    1. Riah says:

      “As an aside, with regard to the T-cell response in unexposed people, I wonder if it’s possible to do a retrospective study of pre-COVID blood donors and evaluate whether the ones with highly active T-cells for CV2 had different outcomes wrt/CV2 (getting it, severity, death, etc.) vs. those with no apparent T-cell cross-reactivity?”

      This has been crying out to be done for the last few months. Why hasn’t anyone followed this up? Or have they/are they right now? If not, why?

  22. TallDave says:

    related topic, what do we think of the Mojiang Mine Hypothesis? seems to rather elegantly explain a number of oddities about COVID without the need for any conspiracies or coincidences

    note that if this is true, the implication is that there is no animal reservoir… might not need years of T cells immunity, if we can wipe it out in humans it’s gone forever

    unless of course it leaks again 🙂

  23. idiotraptor says:

    @TallDave: A bit of inspection reveals that and the site from which it drew the original article you referenced above ( may not be the most credible outlets for science. The Master’s thesis on which the “MMH” is predicated is largely a clinical report and it does indicate the infected individuals contracted a novel coronavirus possible from bat guano. However, no direct sequence data is presented for the novel virus the detected. Without recapping the entirety of the arguments made, the hypothesis advanced above is the Cov that infected some miners may have been the source of SARS-Cov2. It is based on genomic nucleotide identities. Nucleotide sequence and genetic phylogeny analysis are outside my working knowledge domain. There are, however, some serious epidemiologic gaps and, the possibility of coronavirus recombination is not invoked.

    1. TallDave says:

      credible is as credible does… medium is not a scientific publication and this is not a scientific paper

      the source links (there are dozens) must each be judged on their own merits… some are journals, some are major media, etc… all sources have their flaws (cough surgisphere cough)

      claim is not based only on nucleotides, perhaps read further

  24. idiotraptor says:

    BTW, yellow fever virus is transmitted by a mosquito vector. Primates are the reservoir hosts, humans an intermediate host. Human to human transmission is rare.

    1. David G Whiteis says:

      Good point, although there have been catalcysmic human-to-human outbreaks of yellow fever (e.g., Memphis in 1878). Maybe TB would have been a better example.

      But my overall point was that we have drastically reduced the incidence and severity of many epidemic / pandemic-status disease outbreaks without entirely eradicating them, and we’ve continued to live “normal” lives in the process. Of course we’ve learned a lot about hygiene, sanitation, and prevention along the way. But we’ve managed to keep interacating and communicating with one another on an everyday basis in pretty much the same way, through it all.

      (For what it’s worth, it’s been suggested that some of the hard-partying excesses of the “Roaring Twenties” were the result of an explosion of energies that had been pent up during the Spanish Flu pandemice of 1918 and 1919 —

  25. WOW – a tour de force whistle-stop tour of a whole bunch of things in CoV-2 immunity and like everyone else, I’m grateful.

    I think the described peer-reviewed preprint from Sekine et al: is the fourth recent study that discusses cross-reactive T-cell immunity in people that can be shown (or estimated) to not have been exposed to the current virus:

    Grifoni et al:
    Le Bert et al:, and
    Mateus et al:

    And we are left with the connundrum articulated in the present correspondence – of we can show cross-reactivity in the unexposed population (up to 50% in the “Science” report), then where did it come from, and to what extent is it protecting those who display it?

    I’m not convinced by the “it can’t be the common cold” argument, really, because there’s more than one virus caused that inconvenience, and we do not know the proportion of individuals who mount a T-cell response to one of the common-cold coronaviruses, are ever reinfected with that or a related virus.

    I’m much more convinced by the argument that T-cells do “what they are born to do”, as was said above, and am inclined to the side of the fence that believes that a pool of cross-reactive T-cells must confer some degree of protection.

    As for antibodies, they can be very long-lived, but if those that arise naturally in the course of this infection wane after a few months that’s not to say that those induced by vaccination will not last longer.

    Of course, getting such relatively subtle points across to the public and worse, the media, isn’t easy and attempts to do so can be clumsy [ ], particularly when the media want us to believe we’re all going to die if we don’t compulsively mask up [ ]

    Good luck to us all and thanks, Derek


  26. Peter Quennell says:

    Suggestions: (1) Oximeters can warn a week ahead of any test. Provide everybody on Earth with one? (2) NAC boosts glutathione, the most powerful antioxidant, which tends low in (a) selenium poor areas, (2) old people, (3) people originally from the tropics with little or no annual flu. Provide at least all of those with a supply? (3) Have many more ultraviolet airfilters spread around (we have 3 running 24/7 at home)?

  27. Marko says:

    Discussion of mRNA vaccine today in NEJM :

  28. Michael888 says:

    How many of the fishing boat crew died? There was one fatality on the Teddy Roosevelt aircraft carrier with 4800 seaman. In most countries, the young and healthy who contract covid-19 are required to quarantine at home for two weeks; only hospitalized if serious cases.
    Singapore for example has had over 50,000 cases but only 27 deaths, all elderly (median age of fatalities globally is 80; 94-97% of deaths over age 60).

  29. David G Whiteis says:


    If children are, in fact, a previously unacknowledged cadre of asymptomatic superspreaders, what are the implications for the success of a vaccine? The vaccines haven’t been tested on children, and as far as I know it’s not clear at all whether they’ll be approved for pediatric use.

    Even if a vaccine was upwards of 70 – 75% effective among adults, would the coninued possibility of spread among (and from) children seriously sabotage its effectiveness? How does this affect even the most optimistic projections and predictions we’ve seen here?

  30. David G Whiteis says:

    Interesting NYT article, suggesting that the current research on vaccines is actually seriously misguided, since it’s focusing almost entirely on prevention / inoculation, and not on actually stemming transmission. Any opinions?

  31. Jodi says:

    Why do we hear little about some peoples’ ‘natural’ immunity. In the above example seems 13 of the 120 had some natural defense keeping them from being infected. Is it blood type? Past illness with other coronas? Cross protection from other less common vaccines like shingles or yellow fever? Seems to be a significant number always infection free in these ‘super spreader’ events. I believe it’s worth an investigation.

  32. Hopeful Layman says:

    What do the scientific and medical experts here think about this analysis? Is it too optimistic?

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