News broke today, that the mRNA based vaccine against SARS-Cov2 developed by Pfizer and BioNTech (BNT162b2) is 90% effective and is appalling for FDA and EMA approval as early as next week.
The press release sounds promising but does not show any data, just a few numbers.
43,538 participants were enrolled in the clinical trial.
38,955 volunteers have received the two shots (of either vaccine or placebo three weeks apart) as scheduled in the study design so far.
94 cases of Corona infection have been recorded within the study as of today. These are illnesses occurring 7 days after the second shot has been administered.
90% efficiency of the vaccine, protecting the volunteers from a corona infection.
Not showing data of how these cases divide between placebo and vaccine group, these leaves us to do the math: 90% efficiency, meaning that volunteers receiving the vaccine were 90% less likely to contract SARS-CoV2 and develop symptoms compared to volunteers receiving the placebo. So less than 9 individuals, that have received BNT162b2 have contracted symptomatic Covid-19. That is 9 out of 19 477 (if placebo and vaccine were given to equal half of the participants). 85 out of 19 477 in the placebo group got sick.
These numbers do not seem huge at first. And indeed this is an early analysis. The final analysis will take place when 164 cases are confirmed. Which given the second wave currently on the way should be within the next few weeks.
But while the numbers aren’t huge. 9 versus 84 is a big deal and given the final safety data is also good, FDA and EMA approval should go ahead.
In addition to look at Covid-19 cases occurring 7 days after the second vaccination, a second endpoint looking at 14 days is now being added. This addition indicates, that the Covid-19 cases in the vaccine group happen close to the 7 day cut of. The vaccine may just need a bit longer to induce the protective immune response. It will be interesting to see the whole data and not just a few numbers.