According to an November 2020 article from Fox Business:

President Trump had repeatedly said he expected to have the results by the end of October – ahead of the November election.

In a statement on Monday, Pfizer Chairman and CEO Albert Bourla revealed that, following a discussion with the FDA, it decided to drop a 32-case interim analysis – and instead conduct the first analysis at a minimum of 62 cases.

The first interim efficacy analysis was conducted on Nov. 8, at which time the company said there were 94 cases in trial.

A similar question around the 62/94 cases discrepancy is raised by a November 2020 FiveThirtyEight article:

Pfizer was originally supposed to get a peek at the efficacy after 32 volunteers had contracted the disease. But somewhere along the line, the company and the FDA decided together to wait longer, out of concerns that positive results at 32 cases could lead the company to apply for approval too soon. The early look was then supposed to happen after the trial hit 62 cases. But this is where the pandemic itself seems to have collided with the research.

We don’t know exactly what was going on between the 62nd case and the 94th — something Topol, for one, definitely wants more information about.

Is this a allegation true? What is the explanation for Pfizer waiting until 94 cases rather than wrapping up their analysis at 62 cases as suggested earlier by the FDA, possibly reporting the result 2-3 weeks in advance of the election?

Multiple fact check websites have already covered this story and declared the "Pfizer delay" story as fake. However websites like FactCheck.org seem to rely on statements by Pfizer officials to come to a conclusion, such as this one from the CEO of Pfizer:

AB: Sunday we knew that the data are in. So the data came in on Thursday or Friday. And on — but you know, from the time that the data comes in, before the committee meets, some people need to prepare for each case a very big and accurate narrative. And the physician should sign it. So there's a lot of work that needs to be done. But we did it with the speed of light. And once we had the 94 cases, they worked on the narratives, they worked on the tabulation of the results. So on Sunday morning, we didn't want to lose a day, right? They didn't do it Monday. They did it Sunday. The committee met and they reviewed the data.

Is it possible to substantiate these claims without exclusively relying on Pfizer's own statements? In particular, could it be explained by pointing to similar patterns in Astrazeneca/Moderna/J&J announcements or some other piece of tangential evidence explaining the 62-94 cases gap?

  • Comments are not for extended discussion; this conversation has been moved to chat.
    – user11643
    Commented Aug 16, 2021 at 3:18

1 Answer 1


It's probably impossible to examine the actual intent, but I think we can look at whether this decision seems unusual in some way. One way is to compare this first interim analysis with the other approved vaccines that came along at around the same time as well as the general reactions by experts at that time.

The first planned interim analysis was criticized back then as it might simply not have enough statistical power to be meaningful.

The first analysis was to occur after 32 volunteers — both those who received the vaccine and those on placebo — had contracted Covid-19. If fewer than six volunteers in the group who received the vaccine had developed Covid-19, the companies would make an announcement that the vaccine appeared to be effective. The study would continue until at least 164 cases of Covid-19 — individuals with at least one symptom and a positive test result — had been reported.

That study design, as well as those of other drug makers, came under fire from experts who worried that, even if it was statistically valid, these interim analyses would not provide enough data when a vaccine could be given to billions of people.


As a comparison, the first interim analysis for Moderna was performed at 95 cases, which is significantly higher than both the actually performed interim analysis for the Biontech/Pfizer vaccines and the originally planned first interim analysis.

The primary endpoint of the Phase 3 COVE study is based on the analysis of COVID-19 cases confirmed and adjudicated starting two weeks following the second dose of vaccine. This first interim analysis was based on 95 cases, of which 90 cases of COVID-19 were observed in the placebo group versus 5 cases observed in the mRNA-1273 group, resulting in a point estimate of vaccine efficacy of 94.5% (p <0.0001).


As far as I can tell, for Astra Zeneca the first interim analysis was based on 131 cases:

Results of an interim analysis of the Phase III programme conducted by Oxford University with AZD1222, peer-reviewed and published in The Lancet today, demonstrated that the vaccine is safe and effective at preventing symptomatic COVID-19 and that it protects against severe disease and hospitalisation. The interim analysis for efficacy was based on 11,636 participants accruing 131 symptomatic infections from the Phase III UK and Brazil trials conducted by Oxford University.


The Janssen/Johnson & Johnson vaccine performed the interim analysis at an even higher number of 468 cases:

NEW BRUNSWICK, N.J., January 29, 2021 – Johnson & Johnson (NYSE: JNJ) (the Company) today announced topline efficacy and safety data from the Phase 3 ENSEMBLE clinical trial, demonstrating that the investigational single-dose COVID-19 vaccine in development at its Janssen Pharmaceutical Companies met all primary and key secondary endpoints. The topline safety and efficacy data are based on 43,783 participants accruing 468 symptomatic cases of COVID-19.


The interim analysis at 32 cases looks like the outlier here, so I would consider it plausible that this was dropped for scientific and not political reasons. The criticism this endpoint received at that time does support this interpretation.

  • Thanks, that's a good point. Now... do we know anything about when those 94 cases actually happened vs. when Pfizer started processing them? I.e. something in later Pfizer documents giving a timeline of each case? Commented Aug 11, 2021 at 21:34
  • My secondary concern was that even if 94 cases were in fact needed, there's still the question of when Pfizer was notified that 94 have arrived to their desk. Commented Aug 11, 2021 at 21:35
  • 2
    You might also want to include that the FDA got approval from the White House for a 2 month monitoring period in October, which was known to delay results until after the election. abcnews.go.com/Politics/… And articles in the Question state that Pfizer was only expecting to get results in October. Commented Aug 11, 2021 at 21:37
  • 2
    Considering the logic of this answer, it's meaningful to note when all these other companies were at their point of making an interim analysis. They were all long after November, right? Which would negate any reasons of election influence, right? There's also the over-arching "first" motivation they were all pursuing. Then there's the fact that Pharma is more usually a friend to the Right, not the Left. This is why I don't like this question. Motivations are messy.
    – user11643
    Commented Aug 11, 2021 at 23:23
  • 3
    Frankly this Q focused on Pfizer is somewhat odd since Trump blamed the "deep state" FDA in this matter. (And that angle can't easily be disproved by showing that all vaccine-making companies behaved the same way.) Commented Aug 12, 2021 at 14:29

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