Key Points
Pfizer’s Covid-19 vaccine EUA was granted based on early results from an interim analysis from the vaccine’s phase III clinical trial
Deep examination of the results from this analysis suggest that the vaccine has an unfavourable profile with respect to severe events, with an increment of two to three cases of serious adverse events for every single case reduction of severe Covid-19
The samples used for the analyses were selected post-hoc by unblinded investigators and did not follow protocol definitions, which implies possible biases, inflating both vaccine safety and efficacy assessments
Abstract
We demonstrate severe flaws in the procedure of approving Pfizer’s Covid-19 vaccine based on data from the vaccine’s phase III clinical trial. Specifically, we show that according to the official data, at the time the FDA granted the vaccine Emergency Use Authorization (EUA), it had already caused more harm than good: for every reduction of a single severe Covid-19 case, an increment of two to three serious adverse events (SAEs) had been observed in the trial’s vaccine arm. This alone, we believe, should have prevented the FDA from approving this vaccine without further data. In addition, we show significant violations and protocol deviations in the conduct of the trial, which allowed Pfizer to bias the results. In particular, the sample used for the main safety analysis was based on an arbitrary inclusion criteria, and the data cutoff date did not follow the protocol timing. As such, this sample may not be considered a random sample, as required for statistical inference. This implies that the reported results are unlikely to represent a realistic risk-benefit trade-off; in reality, it may be that both the risk is higher and the benefit lower than that reported by Pfizer.