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Here's some more good news. Pfizer/BioNTech's phase 3 trial has concluded after reaching its primary efficacy endpoints, and saw a boost from 90% to 95% efficacy. And this press release at least has more information than the last one. What does it say?
https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-conclude-phase-3-study-covid-19-vaccine
https://www.pfizer.com/news/press-release/press-release-detail/pfizer-and-biontech-conclude-phase-3-study-covid-19-vaccine
-They analyzed 170 total cases from both placebo and vaccinated groups. 162 were in the placebo arm and 8 were in the vaccine arm. Efficacy is calculated based on these 170 cases rather than all 44,000 in the trial.
-No breakdowns for how many of the 170 cases were adults > 65 years old, but they claim the vaccine has 94% efficacy in that demographic group. They claim also that efficacy was consistent across different age, gender, race, and ethnic demographics.
-They list 10 of the 170 cases as "severe," with 9/10 occurring in the placebo group. That's good news, and means the vaccine in this study largely protects against severe disease.
-There's some safety data too: overall it was well tolerated. Based on 8000 of the trial participants, the only "severe" adverse events above 2% were fatigue (almost 4% of recipients) and headache (2%).
-They plan to submit an EUA application to FDA "within days", meaning the vaccine could be on the market by late November or early December.
Overall this is fantastic news, but what don't we know and what does this all mean in the context of the pandemic?
Overall this is fantastic news, but what don't we know and what does this all mean in the context of the pandemic?
Well, we still don't know how this vaccine will perform in a very large population of people. Basing efficacy on 170 cases out of 44,000 participants means that we can't say with certainty if efficacy will remain at 95% in the larger population.
That doesn't mean the trial is flawed or the data is unreliable. There are limitations to extrapolating data from 170 people to the larger, more diverse population of millions of people. I don't expect efficacy to be substantially reduced at population scale, but it may change.
Also, it is still unclear what, if anything, has been done to look at viral loads in the vaccinated cases. This has important implications for transmission. If vaccinated people can get infected and are shedding lots of virus, they could potentially transmit to others.
(Have a call so will come back to this thread shortly)
