The Pfizer COVID-19 vaccine doesn’t prevent transmission: Antivax disinformation goes viral again

Last week there appeared to have been large increase in antivaccine activity on social media, in particular Twitter. I know this mainly because others whom I follow mentioned it, and a certain talking point kept bubbling up to the surface about the Pfizer clinical trial not having tested for the ability of its COVID-19 vaccine to prevent transmission of SARS-CoV-2, which was somehow some sort of horrific oversight that invalidates everything about the vaccine. The whole thing appears to have bubbled up after Rob Roos, a member of the European Parliament, started agitating about vaccine mandates based on this:

It didn’t take long the usual amplifiers of antivaccine misinformation in the media to run with this, including Tucker Carlson:

Antivaxxers were off to the races after this, trumpeting the “revelation” that Pfizer never tested its vaccine to determine if it prevented transmission in its phase 3 clinical trials used by the FDA to issue an emergency use authorization (EUA) for the vaccine in December 2020 and how that failure means that vaccine mandates were always illegitimate right for the beginning.

Antivaxxers and a tsunami of messaging over the last week

Before I explain why this particular line of antivax disinformation is, well, disinformation, I thought I’d include some examples of how it was being spun other than the Tweets above. I’ll start with the antivax and COVID-19 conspiracy site The Epoch Times by way of Robert F. Kennedy, Jr.:

A Pfizer executive said Monday that neither she nor other Pfizer officials knew whether its COVID-19 vaccine would stop transmission before entering the market last year.

Member of the European Parliament, Rob Roos, asked during a session:

Was the Pfizer COVID vaccine tested on stopping the transmission of the virus before it entered the market? Did we know about stopping immunization before it entered the market?

Pfizer’s Janine Small, president of international developed markets, said in response:

No … You know, we had to … really move at the speed of science to know what is taking place in the market.

Roos, of the Netherlands, argued in a Twitter video Monday that following Small’s comments to him, millions of people around the world were duped by pharmaceutical companies and governments.

“Millions of people worldwide felt forced to get vaccinated because of the myth that ‘you do it for others,'” Roos said. “Now, this turned out to be a cheap lie” and “should be exposed,” he added.

Meanwhile, the usual suspects were posting apocalyptic Substacks, for instance Paul Alexander (who, as an advisor to Health and Human Services assistant secretary for public affairs Michael Caputo, noted in a summer 2020 email advocating a Great Barrington Declaration-like “natural herd immunity” approach to the pandemic, “we want them infected“) wrote a post titled “Dr. Geert Vanden Bossche and Dr. Paul Elias Alexander discuss Pfizer’s failure to test COVID vaccines for transmission, the need for population chemoprophylaxis, and recommendations for the vaccinated“. (I like how Alexander uses his full name, including middle name. Who does that?) Regular readers will remember that Geert Vanden Bossche is a veterinarian who made a name for himself fear mongering about mass vaccination during a pandemic in March 2021 because—or so he claimed—imperfect vaccines would drive the emergence of “escape mutants” that could evade prior immunity due to vaccination, ignoring observations that it is the number of people being infected, far more than vaccination, that leads to the emergence of variants that could evade prior immunity, and that these variants could evade prior immunity due to vaccines or previous infection, not just vaccines.

Unsurprisingly, Alexander went on to use that “failure” to start “just asking questions” (a.k.a. JAQing off) about the vaccine, writing “Pfizer (and Moderna) & FDA, the UNHOLIST of alliances, corrupted to the very core, did not test if the COVID gene injection stopped transmission? What else did they not test for? Dr. Koops weighs in“:

Pfizer and Moderna also:

-did not test whether there were any serious drug interactions with other commonly used medicines/vaccines.

-did not test whether there were genetic mutations in the host

-did not test whether the “vaccine” became systemic or stayed restricted to the injection site

-did not test whether “boosters” were actually beneficial (they simply stated that as the initial protocol as a two dose protocol without any data to support it)

-did not test whether the “non-active” ingredients caused any problems (these were not normal excipients-some of the placebo arm data suggests that these were also causing problems)

-did not test whether the “vaccine” was transmissible from the recipient

-did not test as to metabolic elimination of the vaccine from the host, i.e. how long does it remain active in the host

-proposed a product specification that would essentially allow for almost anything to pass

-did not account (i.e. screen) for a rather pronounced natural immunity already in the population

-conducted most of their studies outside of the US in countries that have been known for questionable clinical studies (Brazil in particular)

-had virtually no stability data

One notes that we’ve addressed a number of these claims before; so I will not address them again, except to note a couple of common tropes. As for “natural immunity already in the population”, remember that the Pfizer vaccine was tested in the summer and fall of 2020, before a huge percentage of the population had become infected. Similarly, the mRNA-based vaccines produced by Pfizer and Moderna do not “permanently alter your DNA,” contrary to Alexander’s other claim.

Elsewhere, “health freedom groups” trumpeted “We tried to warn you“, while James Lyons-Weiler proclaimed, “Knowledge About Lack of Protection Against Transmission is Old, Not New“. Indeed it’s not, as we will show (and as even The Epoch Times article acknowledged), nor is it shocking. Lyons-Weiler tries to spin this as:

The admission by a Pfizer exec has set social media ablaze with shock. That’s what you get when you suppress inconvenient truths. Now the flawed policies must be reversed or rescinded.

That’s right! Antivaxxers are treating this “revelation” as some sort of shocking “new” news when its not, and Lyons-Weiler tries to say that the reason they’re doing this is because there was a conspiracy to cover up this “inconvenient truth”. But was there? (I think you know the answer to that.)

Before I get to that question, I’ll note that this isn’t all the antivax content, not by a long shot, seemingly coordinated to amplify the message that the approval of the Pfizer vaccine was illegitimate because it never tested for the ability of the vaccine to prevent transmission. There were, of course, many videos, because there are always antivax videos, from the usual suspects. For example, over at Rumble, Alexander interviewed Vanden Bossche about the same thing, with largely the same claims. COVID vaccine transmission. Meanwhile, John Campbell (whom we’ve met before spreading misinformation about COVID-19 and monkeypox and someone whose misinformation we at SBM should really have discussed more often) treats this “revelation” as something new that had been hidden for nearly two years, introducing his story with the exchange between Robert Roos and Janine Small, Pfizer’s president of international developed markets before describing the revelation as a “breaking international scandal”—and, near the end of his video, a “complete and utter scandal”—that Pfizer did not know whether its vaccine stopped transmission before rollout:

Around 1:27 he goes on about how:

…at the time I remember representatives of the UK government who’ve now been made into Dames and Knights and all sorts of things emphatically telling us that everything that was normally done in any clinical trial was done during these trials. They gave us their word about this, and let’s hope that this doesn’t turn out to be less than accurate.

Susan Oliver did a nice job of deconstructing Campbell’s disinformation, as usual, but I’ll discuss some of it with my spin as well, as my purpose in writing this post is not so much to point out why this whole “shocked” line of hysteria is nothing new and based on intentionally deceptive spin and outright lies, but to look at the history as well, which makes me perfectly happy to point you to sources in addition to my scintillating words to deal with this particular antivax propaganda:

Let’s dig in. First, I think it’s important to address a seemingly simple but poorly understood question: What is the purpose of a vaccine?

The purpose(s) of a vaccine

So what are the purposes of a vaccine, anyway? I say “purposes” because vaccines don’t have just one purpose. First and foremost, the main purpose of a vaccine is to prevent people from becoming seriously ill due to disease caused by a pathogenic microorganism such as a virus or bacterium, period. If a vaccine doesn’t do that, it’s a pretty useless vaccine, particularly in the middle of a pandemic that by late 2020 had killed over a quarter of a million people in the US alone. Ideally, the second purpose of a vaccine is to prevent infection and transmission; i.e., to prevent the pathogenic organism from getting established in a vaccinated host human in the first place and to render that person unable to spread the pathogen to others. This phenomenon is called “sterilizing immunity” and means that the immunity produced by a vaccine is so effective that the virus cannot replicate in the vaccinated individual sufficiently to gain a foothold and cause infection, much less be transmissible by that person to others.

Most vaccines that prevent severe disease also prevent transmission to at least some extent, even if far from being able to produce sterilizing immunity, and vaccines that aren’t very good at preventing infection and transmission, even if they are good at preventing severe illness, are referred to as “leaky”. I discussed this concept in a fair amount of detail when I discussed Geert Vanden Bossche’s claim that, because COVID-19 vaccines are “leaky”, they select for nasty variants in the presence of mild or asymptomatic disease in the vaccinated. I also mentioned how this particular claim is not new among antivaxxers, citing the example of long-time antivaccine activist and scientific fraudster Andrew Wakefield, who made exactly the same claim for the measles vaccine, fear mongering about a sixth “mass extinction” because of the MMR vaccine.

Ironically, I also cited an article published in Scientific American in January 2021 titled “Vaccines Need Not Completely Stop COVID Transmission to Curb the Pandemic“, when the Pfizer and Moderna COVID-19 vaccines were starting to roll out to populations other than healthcare workers and very high risk individuals, that explained that quite a few vaccines that we commonly recommend are not perfect at preventing transmission. It was an excellent article that’s worth revisiting one more time before I discuss the Pfizer clinical trial.

Here’s the key point:

Although many vaccines widely used today (against measles, for example) produce very effective sterilizing immunity, others, such as the hepatitis B vaccine, do not. With these vaccines, an individual’s immune system is trained to prevent illness, yet the pathogen can persist in that person’s body, potentially allowing them to infect others. A lack of sterilizing immunity means that the pathogen can continue to circulate in a population, where it may cause illness in unvaccinated and vulnerable people or evolve to evade our immune responses, Bowdish explains.

And another example:

The case of rotavirus—which causes severe vomiting and watery diarrhea and is especially dangerous to infants and young children—is fairly straightforward. Vaccination limits, but does not stop, the pathogen from replicating. As such, it does not protect against mild disease. By reducing an infected person’s viral load, however, it decreases transmission, providing substantial indirect protection. According to the Centers for Disease Control, four to 10 years after the 2006 introduction of a rotavirus vaccine in the U.S., the number of positive tests for the disease fell by as much as 74 to 90 percent.

Another favorite example frequently cited by antivaxxers before the pandemic is pertussis, because the vaccine doesn’t produce sterilizing immunity:

For example, vaccines against Bordetella pertussis, the primary bacterium that causes whooping cough, or pertussis, do a great job of preventing illness but do not entirely clear the pathogen. Rather, as B. pertussis replicates in the upper respiratory tract, vaccine-induced antibodies apply pressure via natural selection to weed out bacteria whose disease-causing genes are turned on. Because these same genes are responsible for the parts of the microorganisms that are targeted by antibodies, bacteria that keep them turned off evade the immune response and hang out undetected in the upper respiratory tract, Bowdish explains. This becomes a problem when someone with a naive immune system, such as an infant, contracts the pathogen. In the absence of antibodies, B. pertussis‘s disease-causing genes become activated again, causing illness. Nevertheless, the introduction of pertussis vaccines in the 1940s cut annual U.S. cases from more than 100,000 to fewer than 10,000 by 1965. In the 1980s cases began slowly climbing again as parents increasingly refused to vaccinate their children. Today there is renewed focus on reducing the chance of exposure and getting antibodies to infants by immunizing pregnant women and new mothers.

I’ve noted many times that antivaccine “thinking” about vaccines tends to be very black and white. Either the vaccine is 100% effective, or it’s useless crap; the vaccine is either 100% safe, or it’s deadly enough to cause a “vaccine holocaust“; either the vaccine prevents transmission 100% or it “doesn’t stop transmission” at all! Again, in medicine, as in life, nothing is 100% certain except that each and every one of us will one day die, and efficacy for any intervention exists on a spectrum. That’s why, in general, even a nonsterilizing vaccine can be very, very useful. Indeed, in December 2020, even a completely nonsterilizing vaccine that didn’t prevent transmission at all but was effective at preventing severe disease would have helped to prevent enormous numbers of people ending up in the ICU and/or grave.

Before any antivaxxer cries, “Straw man!” out there, I do realize that the main point of this particular conspiracy theory about Pfizer not having tested its vaccine for its ability to prevent transmission is not to claim that it doesn’t prevent severe disease (although, to be sure, antivaxxers do that a lot too) but to call into question the legitimacy of its approval by the UK and EUA in the US, in particular to claim that COVID-19 vaccine mandates were based on no data. I’ll get to that in a minute, but first let’s look at the actual Pfizer trial.

The Pfizer trial

As Susan Oliver (and many others) noted, the results of the phase 3 clinical trial of the Pfizer BNT162b2 mRNA-based vaccine were published in The New England Journal of Medicine on December 31, 2020. It’s right there in the paper’s methods section:

The first primary end point was the efficacy of BNT162b2 against confirmed Covid-19 with onset at least 7 days after the second dose in participants who had been without serologic or virologic evidence of SARS-CoV-2 infection up to 7 days after the second dose; the second primary end point was efficacy in participants with and participants without evidence of prior infection. Confirmed Covid-19 was defined according to the Food and Drug Administration (FDA) criteria as the presence of at least one of the following symptoms: fever, new or increased cough, new or increased shortness of breath, chills, new or increased muscle pain, new loss of taste or smell, sore throat, diarrhea, or vomiting, combined with a respiratory specimen obtained during the symptomatic period or within 4 days before or after it that was positive for SARS-CoV-2 by nucleic acid amplification–based testing, either at the central laboratory or at a local testing facility (using a protocol-defined acceptable test).

Major secondary end points included the efficacy of BNT162b2 against severe Covid-19. Severe Covid-19 is defined by the FDA as confirmed Covid-19 with one of the following additional features: clinical signs at rest that are indicative of severe systemic illness; respiratory failure; evidence of shock; significant acute renal, hepatic, or neurologic dysfunction; admission to an intensive care unit; or death. Details are provided in the protocol.

In other words, the primary endpoint for efficacy was clinical, symptomatic disease confirmed by laboratory testing, and the secondary endpoints were efficacy against severe disease, not transmission or asymptomatic infection. Again, it’s all right there in the methods.

It was also in the FDA press release dated December 11, 2020:

At this time, data are not available to make a determination about how long the vaccine will provide protection, nor is there evidence that the vaccine prevents transmission of SARS-CoV-2 from person to person.

Interestingly, the Epoch Times article cited by RFK Jr. specifically quotes the above statement:

The U.S. Food and Drug Administration wrote in late 2020 that there was no data available to determine whether the vaccine would prevent transmission and for how long it would protect against transmission of the SARS-CoV-2 virus that causes COVID-19.

“At this time, data are not available to make a determination about how long the vaccine will provide protection, nor is there evidence that the vaccine prevents transmission of SARS-CoV-2 from person to person,” the agency specifically noted.

Meanwhile, Pfizer CEO Albert Bourla, around the same time, said his firm was “not certain” if those who receive its mRNA vaccine will be able to transmit COVID-19 to other people.

“I think this is something that needs to be examined. We are not certain about that right now,” Bourla told NBC News in December 2020 in response to a question about transmissibility.

And in a UK guidance document dated June 8, 2021 (thanks to Dr. Oliver without whom I probably wouldn’t have found this one):

Clinical trial evidence demonstrates that the vaccine reduces clinically severe infection and severe disease. The impact of the vaccine on preventing transmission remains unknown and individuals who have been vaccinated may still carry and be able to transmit the virus. We advise anyone who has been vaccinated to continue to observe national lockdown restrictions and engage with asymptomatic LFD and PCR testing if appropriate

Meanwhile, in January 2021, scientists were noting:

Current estimates of the level of effective population immunity for interruption of transmission is ~60–70%, but vaccination coverage required by a partially effective vaccine to interrupt transmission might be higher. With 8 billion people to vaccinate with a two-dose regimen, we might need 10–11 billion doses to interrupt transmission.

In other words, the vaccines were not being sold as a panacea, at least not by the scientific community.

But wait! Antivaxxers will say that this was all buried in clinical trial methods, FDA press releases, and government guidance documents that no one reads! That’s how “they” covered it up! Unfortunately, it’s not hard to find contemporaneous examples of press reporting that did no such thing. For instance, this Washington Post article explained that the trial didn’t look at the ability of the vaccine to prevent transmission:

Major questions that remain unanswered about the vaccine include how long the protection will last and whether the vaccines prevent people who are infected despite vaccination from spreading the disease.

The trial showed no evidence that immunity subsided during the two months after the second dose, but more data will need to be gathered to assess whether protection tapers off. The reviewers called for further study of whether people, particularly those with asymptomatic infections, spread the disease. Epidemiologists have worried about a worst-case scenario in which people who are vaccinated stop wearing masks but may become asymptomatically infected and spread the disease.

“It is possible that if efficacy against asymptomatic infection were lower than efficacy against symptomatic infection, asymptomatic cases in combination with reduced mask-wearing and social distancing could result in significant continued transmission,” the review states.

In other words, it was not kept a secret that, in December 2020 at least, we did not yet know how well (or even if) the Pfizer vaccine could prevent transmission of SARS-CoV-2 because that’s not what the clinical trial was designed to do. Nor, contrary to claims from antivaxxers like Campbell, do most phase 3 trials for vaccines examine transmission as an endpoint to be used for licensure, as Susan Oliver explains in her video, citing trials of various measles and HPV vaccines. To that I’ll add some other vaccine trials, including this one of a rotavirus vaccine in which prevention of transmission was not an endpoint or clinical trials of Rotateq, for which—again!—prevention of transmission was not an endpoint.

Dr. Oliver also very nicely hoisted Campbell on his own petard, including a video from May 2021 (which was before he’d become an antivaxxer), in which he demonstrated that not only did he know why the complaint that the Pfizer trial didn’t assess the ability of its vaccine to block transmission but cited a result from the paper suggesting that the vaccine likely was very effective in actually—you guessed it—blocking transmission:

Again, the purpose of clinical trials of vaccines is to determine if the vaccine is safe and effective at protecting the recipient against the disease targeted. You might reasonably ask why vaccines are usually not tested for their ability to prevent transmission in phase 3 trials. The answer is fairly simple and two-fold. First, again, the primary purpose of a vaccine is to prevent disease and death from infectious microorganisms. Everything else, including prevention of transmission, is gravy. Second, study designs to identify interruption of pathogen transmission are different than for determining efficacy and safety, which is why they are best carried out during post-licensing surveillance, not during the randomized controlled phase 3 trial for licensure:

Conversely, RCTs might underestimate the protective effect of vaccines at the population level. This would occur if the COVID-19 vaccine, in addition to conferring direct protection to individuals, reduces transmission of COVID-19 between individuals, providing protection to unvaccinated individuals and enhanced protection of vaccinated individuals in contact with vaccinated individuals. Vaccine-induced herd protection, which might be crucial to the public health value of a vaccine, will be missed when trials are individually randomized and analyses fail to take account of the geographical distribution of individuals in the population. Table 1 provides a summary of estimates of the basic reproduction number, herd immunity, efficacy and effectiveness for several vaccine-preventable diseases. The definition of effectiveness might vary by study.

In general, “effectiveness” includes the ability of the vaccine to prevent infection and transmission:

Collection of effectiveness data and understanding indirect protective effects of vaccination will allow countries to make rational plans for maintaining herd protection

Remember, all of this was published around the time the vaccines were introduced and shortly after.

Another bit of antivaccine messaging around the Pfizer trials seeks to impute nefarious intent as Pfizer went from earlier stage clinical trials to its phase 3 trial. Sadly, some of this misinformation showed up in the comments of my not-so-super-secret other blog:

Pfizer’s phase-1/2 trial did indeed study antibodies which is the best gauge for assessing transmission. Binding antibodies was reported for the 45 subjects but crucial neutralizing antibodies was only assesed [sic] for only seven subjects with Pfizer promising that data was forthcoming. I don’t believe it ever got reported before they eventually switched to assessing whether the vaccine prevented symptoms for the phase-3 trial.

https://pubmed.ncbi.nlm.nih.gov/32785213/

And then, in another comment of my not-so-secret other blog:

Further to my comment above and speaking of shifting goalposts, the mother of all goalposts shifts occurred when Pfizer moved from studying efficacy of its vaccine by its immunogenicity profile in phase-1/2 to assessing symptoms in phase-3. This goalposts shift went largely unnoticed; drowned out by the thunderous fanfare and jubilation that proceeded the phase-3 trial news that the vaccine was 95% effective at preventing symptoms. And, perhaps the shift would’ve remained inconsequential if the vaccine hadn’t now proven to be ineffective at stopping shit.

Let it be known that it’s not just a case of Pfizer not assessing whether its vaccine is effective at stopping transmission, but them deliberately choosing this.

First, this commenter didn’t bother to scroll down and see under “Similar articles” this follow-up article in which antibody levels and T-cell responses were reported. Second, only someone who has no clue how clinical trials proceed from preliminary to phase 3 could write something this ignorant. The purpose of phase 1 trials of vaccines is to assess gross safety; i.e., that the vaccine doesn’t cause any obvious toxicity detectable in a relatively small number of patients. In other words, it’s looking for obvious and serious safety signals before larger trials are done, usually also with correlative studies of the vaccine’s ability to provoke an antibody response to the antigen. Phase 2 trials look at a larger number of patients and are focused on looking for signals of efficacy (in the case of vaccines, immunogenicity) and more safety data. However, by the time you get to the phase 3 trial, what a regulator really wants to know before approving a vaccine is whether the immunogenicity detected in earlier phase trials actually translates into prevention of disease. That’s where the rubber hits the road. If the immune response and antibodies detected in phase 1 and 2 trials don’t translate into a significant prevention of disease, then the vaccine is indeed useless. So, yes, Pfizer did deliberately choose not to assess interruption of viral transmission and likely did so in consultation with the FDA, which frequently advises companies on what it needs to see in the clinical trials carried out to support the approval of an investigational drug or vaccine.

Do COVID-19 vaccines prevent transmission?

The antivax propaganda message of ‘the clinical trials used as the basis for an EUA of the Pfizer vaccine never examined whether the vaccine can prevent transmission’ reminds me of Peter Doshi’s obsession—shared by many antivaxxers—with the original clinical trials used to license the Pfizer and Moderna vaccines. How? This line of disinformation intentionally completely ignores what we have learned during the nearly two years since the publication of the results of those phase 3 clinical trials in favor of falsely portraying the phase 3 trials as the be-all and end-all of what we know about the efficacy of the vaccines in preventing transmission, rather than as a starting point sufficiently robust to issue an EUA for the vaccines. It is true that we knew little or nothing then about how effective the Pfizer vaccine was in preventing onward transmission of the coronavirus, but It’s not as though we haven’t learned anything since then regarding whether the Pfizer and Moderna vaccines (as well as the other existing COVID-19 vaccines) are able to prevent transmission. Quite the contrary. There are literally dozens of studies of just the Pfizer vaccine (originally named BNT162b2) alone for the primary course and for boosters for the original strain of SARS-CoV-2 as well as the Delta—and now Omicron—strains. These are all ignored by antivaxxers promoting this narrative.

Susan Oliver cited two of these studies, including an early one that I used to cite last year from April 2021 that showed that, among healthcare workers in England, the vaccine was very effective in preventing both symptomatic and asymptomatic infection and a more recent one from Denmark that demonstrates that vaccination does reduce transmission, even with the more recent immune-evading variants Omicron BA.1 and BA.2.

It is, unfortunately, quite true that vaccines are less effective at preventing transmission of the Delta and Omicron variants, which is not unexpected given that these strains have evolved changes in the protein sequence of their spike proteins that make antibodies produced by the vaccine less effective in neutralizing the virus. For instance, this study from Belgian used contact tracing to estimate vaccine effectiveness against transmission (VET) for the original SARS-CoV-2 strains and Delta variants:

VET-estimates were higher for mRNA-vaccines, over 90%, compared to viral vector vaccines: 66% and 80% for Ad26COV2.S and ChAdOx1 respectively (Alpha, 0-50 days after vaccination). Delta was associated with a 40% increase in odds of transmission and a decrease of VEs (72-64%) and especially of VEi (71-46% for BNT162b2). Infection-acquired and hybrid immunity were less affected by Delta. Waning further reduced VET-estimates: from 81% to 63% for BNT162b2 (Delta, 150-200 days after vaccination). We observed lower initial VEi in the age group 65-84 years (32% vs 46% in the age group 45-64 years for BNT162b2) and faster waning. Hybrid immunity waned slower than vaccine-induced immunity.

There is also good evidence that mRNA-based vaccines against COVID-19 can prevent transmission among children and even in high-risk situations, such as among the residents of nursing homes and long-term care facilities. Additional evidence suggests that the VET fell for the Delta variants. For Omicron variants, particularly the BA.4 and BA.5 variants, there is less evidence published given that the variant took off a year ago and it takes many months to do these kind of epidemiological studies, but there is still a growing body of evidence (for example, this) that Omicron variants can evade prior immune responses from vaccines and from infection with previous SARS-CoV-2 variants, but that does not mean that the vaccines “don’t prevent transmission,” but rather that they still do prevent transmission, just not nearly as effectively as they did for the original strain against which they were designed to protect. (There’s that black-and-white thinking again characterizing a vaccine that is only partially effective against preventing transmission as “not preventing transmission” at all.) That is not surprising and is why updated vaccines will be important in the future, particularly given that Omicron has demonstrated itself to be able to evade “natural immunity” due to prior infection with a previous strain of SARS-CoV-2, such as Delta or the original strain that emerged from Wuhan.

Why is this message being resurrected now?

Again, there is nothing new here. Indeed, Dr. Allison Neitzel of the Counter Disinformation Project led me in her weekend roundup to a whole Tweet thread documenting how long antivaxxers have been hitting this particular fake criticism noting what a short memory antivaxxers have:

I could go on, but you can follow the whole thread for more. Some of the Tweets date back to December 2020, making this one of the oldest COVID-19 antivax talking points there is.

All of this leads me to wonder: Why are antivaxxers resurrecting this particular message now? The best reason I can come up with is that it’s opportunistic. Rob Roos thought he got a “gotcha moment” from a Pfizer executive, which caught the attention of Tucker Carlson’s producers, which led to him appearing on Tucker Carlson’s Fox News show last week, which amplified the message by providing convenient suspicious-looking (and misleading) clips that antivaxxers could share on social media and that antivax influencers like Paul Alexander could share on their Substacks, RFK Jr. could amplify on his website, and vloggers like John Campbell could make viral videos about. Add to that the human tendency towards black-and-white, either-or thinking in which, instead of existing on a continuum, people tend to conclude that a vaccine is either effective or not, safe or not, and you have a perfect storm of antivax propaganda, particularly when a conspiracy theory is suggested in which Pfizer and the government “covered up” the lack of data on forward transmission in the phase 3 clinical trial, all in order to enforce vaccine mandates as protecting others. The interesting thing is that the Moderna phase 3 trial for its vaccine (mRNA-1273) used a very similar design to Pfizer’s phase 3 trial and also did not examine virus transmission as an endpoint, but I’m not seeing this claim applied to that vaccine. This further suggests the opportunistic nature of this particular outbreak of viral disinformation.

Dr. Neitzel suggests politics as the reason, and she could have a point:

That all the usual characters have jumped on this at the same time feels like an effort to build on the escalation in previous weeks. In the US this appears to be an effort to mobilise the anti-vax base in preparation for the mid-term elections next month when many disinformation doctors are standing for office.

We see far-right groups in Canada and Europe seeking to capitalise on this while in the UK Richard Tice’s Brexit Party has transformed into the sceptic Reform Party which is seeking to benefit from the chaos within the Conservative Party. Several other parties like the far-right English Democrats and Heritage Party which are working with disinformation groups are trying to do the same.

Whether she’s correct or not, I note that none of this is new. Those of us who’ve followed antivaccine messaging for a long time have seen it all before, be it with the pertussis vaccine or even with the measles vaccine, for the latter of which apparently 95% efficacy at preventing infection is not good enough for antivaxxers to accept that it works. The pandemic has vastly amplified the voice and reach of antivaxxers promoting such conspiracy theories. Each antivax narrative like this one in which Pfizer and the FDA supposedly “hid” the fact that the phase 3 clinical trials for the Pfizer vaccine didn’t test for its ability to prevent transmission pops up, disappears, and then pops up again elsewhere, resulting in an endless and frustrating game of Whac-A-Mole for those dealing with disinformation. That’s the idea. There is no doubt that this kerfuffle will fade, only to be resurrected again when a piece of news makes it convenient for antivax disinformation peddlers like Roos to resurrect it. That’s why, increasingly, I am coming to think that prebunking the form of antivax disinformation will be more important going forward than just trying to whack each mole as it pops up.