Why Weren’t There More Cases of COVID-19 During the Pfizer Trial?

It has been nearly impossible to keep up with all the additional data emerging about the COVID-19 vaccine from both Pfizer and Moderna TX. I already feel like I need to make many updates to my guide, Everything You Need to Know About the COVID-19 Vaccine. However, I don’t want to put out a brand new copy every time there is the tiniest update in my analysis. So, I thought, instead I would give you a quick sneak peek here in a blog post, to get the information out and the wheels turning.

New Data on Efficacy Hidden Within the Pfizer Trial

We have all heard multiple times that the Pfizer vaccine’s efficacy rate is somewhere around 95%. This efficacy rate is defined from the following data (from the same source), “The first primary objective analysis is based on 170 cases of COVID-19, as specified in the study protocol, of which 162 cases of COVID-19 were observed in the placebo group versus 8 cases in the BNT162b2 group.”

The first thing I thought after reading this data was, “one hundred and seventy cases is an incredibly small sample size to base complete efficacy data from.” Especially when the entire purported population of the study was over 35,000 individuals. It seems as though these were the only cases based on the way that efficacy has been reported by Pfizer as well as by the FDA However, we are often reminded that cases are skyrocketing, in the US and all over the world, so, even though the study period was quite short, should we not have seen more cases in the placebo group at least?

Why Weren’t There More Cases of COVID-19 During the Trial?

The answer to this question is twofold. First, we must recognize that Pfizer did not start counting COVID cases until seven days after the second dose of the vaccine. As we look more closely at the data linked above, we see that there were more cases than those used to hit the phase three end goal. They were just not counted.

This graph shows the cases after the FIRST dose. That means that the circled cases, (days 0-21) were never counted when confirming efficacy.

COVID Cases After Day 1 (Circled data not included in their Analysis)

This explains where some of the cases of COVID-19 went. The second part of this question is a little bit more complicated to answer. We have to ask ourselves another question– is it possible that there were more cases in both the placebo and the vaccinated group? If we take a look at page number 42 of Pfizer’s data we find this:

3,410 would be a much more appropriate number of cases for such a large scale study such as this. It is also fascinating that 1594 of these cases appeared in the vaccinated group. A much closer ratio to the 1,816 cases in the placebo group. Based on this, the efficacy rate would be much closer to 50%. However, these cases were not included in the overall analysis because they were never “confirmed” as COVID cases.

Questions about the Data

This data brings up a lot of questions. Pfizer was meant to continue to test anyone who reported symptoms or urge them to get a test taken. This protocol is listed in the study design portion source above. So, why were these cases not confirmed? Why were they not tested? Why were they not included in the original efficacy data? Well, of course, as stated above, many of these were not counted because they happened before day 21.

Apparently, 696 of the 3,410 unconfirmed cases happened within 7 days of any vaccination, but, what about the rest? What is really important here, for efficacy’s sake, is how many in the vaccinated group got sick 7 days after the second dose of the vaccine? However, that analysis was not included in Pfizer’s data. 

Because these cases were never confirmed, we do not have a fuller picture of what efficacy looks like, nor do we know, as stated in Pfizer’s report, if these suspected cases were masking adverse events after vaccination. Both are very important to know in order to truly measure the success of the vaccine. However, we are left to collect “post-marketing data,” because of the lack of care taken in the trial to identify all cases of COVID-19.

If you would like to get more in-depth analysis on the COVID-19 vaccine, please download our guide, Everything You Need to Know about the COVID-19 Vaccine. I will continue to update you on new pieces of information like this here as well as frequently updating the guide so you can have all the data for yourself.

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UPDATE: 1/21/20

A few days after I wrote this post an article in the BMJ written by Dr. Peter Doshi, (the editor), crossed my path. Dr. Doshi wrote a very similar article to mine. He has calculated the effectiveness rate of the Pfizer vaccine to be closer to 29%. Just as I do, he sees a need for Pfizer to be transparent and come forward with the full dataset.

He continues to point out many flaws in the trials, including the exclusion of those who have already had Sars-Cov-2 in the trial and the imbalance in excluding too many participants in the vaccine group on the part of Pfizer. It is worth reading and validates much of the work I have done here and the questions we are raising. Take a look.

Everything You Need to Know about the COVID 19 Vaccine

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