Brownstone » Brownstone Institute Articles » Fact Checkers on Viral Transmission: They Get It Wrong Yet Again

Fact Checkers on Viral Transmission: They Get It Wrong Yet Again


One of the more bizarre “fact-checks” I’ve seen so far is this one from a particularly sloppy censorship outlet called Lead Stories. It seems to be concocted in response to trending news of a Pfizer executive stating that their Covid-19 vaccine was never tested for efficacy against transmission. Rob Roos, Member of the European Parliament shared the executive’s reply on Twitter, with his own comments.

This breakthrough piece of research is written by one Madison Dapcevich, who holds a master’s degree in environmental science and natural resource journalism from the University of Montana. So, clearly a top expert in medicine.

This is headline of Dapcevich’s article:

“Fact Check: Pfizer Vaccine Clinical Trial NOT Intended To Test Transmission Prevention — That’s Not How Clinical Trials Work”

As Dapcevich explains:

“Did a Pfizer representative “admit” the company erred when its COVID-19 vaccine was “never tested on preventing transmission” of the virus during clinical trials? No, that’s not true. Vaccine clinical trials for drug approval are not meant to test that. Clinical trials are intended to check the safety and efficacy of new drugs and vaccines before they are approved for widespread use. Testing for the prevention of disease transmission is not typically part of initial trials, according to vaccine experts. In this case, the vaccine’s ability to prevent transmission was assessed later in the roll-out of the vaccine, which was developed in response to a worldwide pandemic.”

To start with, the Pfizer representative did say the vaccine was not tested against transmission. So obviously it IS true that the representative said this. The fact that the author of the tweet, which Dapcevich uses as the starting point for her “fact-check”, clearly believed the Pfizer representative; using the word “admits”, is besides the point: The question is, if the representative said this. She did. Dapcevich is wrong to claim she didn’t.

Second, neither the Pfizer executive nor the parliamentarian ever said that the company “erred” by not testing if their vaccine limited transmission. This is Dapcevich’s own concoction, typical of the strawman approach commonly used by her and her kind.

Dapcevich then moves on to claim that vaccine trials are not meant to test for transmission, while at the same time claiming they are intended to check for efficacy against infection:

“While Pfizer and Moderna vaccines were shown to protect against illness and severe disease, the Association of American Medical Colleges notes vaccine clinical trials are not “designed to test whether any of the trial participants contracted COVID-19 but showed no symptoms.”

In short, the trials that tested the safety and efficacy of the vaccine were not designed to test transmission in part because the trial size and duration would have needed to be larger and longer and the goal was to prevent deaths.”

The reasoning is interesting: The author quotes the claim that the trials do not test for asymptomatic infection. From this she draws the conclusion that this has to do with “trial size and duration” which is not stated in her premise at all, and that the “goal was to prevent deaths” which isn’t stated either and is obviously false to anyone who has read the study. Her final conclusion is that vaccine trials do not test for transmission at all. Not only is Dapcevich an undisputed authority on medicine, she clearly possesses truly exceptional logical skills also.

In the real world however, when it comes to vaccines, efficacy is exactly about infection; whether the vaccine prevents infection or not. And this is precisely what was tested during the Pfizer trials. In the authors’ own words: 

“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).”

“Among 36,523 participants who had no evidence of existing or prior SARS-CoV-2 infection, 8 cases of Covid-19 with onset at least 7 days after the second dose were observed among vaccine recipients and 162 among placebo recipients. This case split corresponds to 95.0% vaccine efficacy (95% confidence interval [CI], 90.3 to 97.6; Table 2).”

“In the context of the current, still expanding pandemic, the BNT162b2 vaccine, if approved, can contribute, together with other public health measures, to reducing the devastating loss of health, life, and economic and social well-being that has resulted from the global spread of Covid-19.”

In short, the trial was about checking for “confirmed Covid-19” by the presence of at least one of the symptoms ascertaining Covid-19 infection and the conclusion is that the vaccine will help end the pandemic.

It is true that asymptomatic infections, at the time believed to be up to half of all infections, were not checked for in the trial. It is also true that late in 2020 Pfizer CEO Albert Bourla expressed concerns that the vaccine might not prevent asymptomatic transmission. But this does not mean the trial was not designed to check for infection and thereby for transmission. It only means the check was partial, not full.

Therefore Dapcevich’s claim, stated in her headline and repeated several times in the article, that the clinical trial was “NOT intended to test transmission prevention” and that “That’s Not How Clinical Trials Work” is simply wrong.

On the contrary, the primary endpoint of the study had to do with infection and without infections there will be no transmission. And as we see in the last quoted passage, from the discussion part of the study, the authors even explain how the vaccine will reduce, not only loss of health and life, but also of “economic and social well-being.” This means the authors believe the study shows that by vaccination Covid-19 countermeasures can be eased, which of course means they believe the vaccine will prevent transmission.

There was no question of this at the time. Politicians and propagandists such as Anthony Fauci went right ahead to state that the only thing preventing the efficacy from translating into real-world effectiveness was participation in the vaccination programs. 

What is the real story then? At the hearing, the Pfizer representative said reduction of transmission was never checked for. But as the trial study shows, this was checked; it was the primary endpoint of the study.

There are three key takeaways:

First, the author of the fact-check article wrongly claims that clinical trials of vaccines are not intended to test transmission prevention.

Second, by adding the word “err” into Roos’s statement, the author “fact-checks” a statement that was never made.

Third, the Pfizer executive was wrong to claim in the hearing that transmission was never tested for. It was, and that was the main reason for the trial. A proper fact-check headline would therefore have read:

“Fact Check: Pfizer Executive Wrongly Claims Transmission Prevention Not Tested in Clinical Trial — That’s Exactly What Was Done”

The question remains if the Pfizer trial was in fact flawed and/or the company’s behaviour dishonest. The trial results have from the start been used to justify draconian attacks on and exclusion of unvaccinated people, for a long time the 95% efficacy claim was relentlessly touted to support mass-vaccination, and those who doubted this, pointing to actual data, immediately became the targets of “fact-checkers” like Madison Dapcevich and were subsequently censored by social media, smeared and ostracised.

Pfizer never issued any clarifications regarding the methodology, but instead bragged about how their shot would end the pandemic. Furthermore, as at the time it was already believed that up to 50% of those infected never showed any symptoms there was already a strong reason to use pcr tests rather than just checking for symptoms in the trial.

So, did the company “err” after all? It may well be argued that it did, and perhaps not by mistake, but by intention. Did the politicians err, the propagandists, the media? Did the fact checkers err? They surely did, they keep it up, and they do it by intention.


  • Thorsteinn Siglaugsson

    Thorsteinn Siglaugsson is an Icelandic consultant, entrepreneur and writer and contributes regularly to The Daily Sceptic as well as various Icelandic publications. He holds a BA degree in philosophy and an MBA from INSEAD. Thorsteinn is a certified expert in the Theory of Constraints and author of From Symptoms to Causes – Applying the Logical Thinking Process to an Everyday Problem.


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