FDA Pfizer booster meeting update


As promised, I wanted to give you a summary of last week’s meeting on boosters. For us data-epid-nerds, these meetings are a gold mine of rigorously designed studies and all the data you could ever want. =) Ok, buckle up friends. Here we go. Also, I included screenshots from today’s meeting that are not the best quality. They all came from the FDA’s meeting linked above unless otherwise noted.


Dr. Sara Oliver (which, BTW, is an incredible presenter and scientist/epidemiologist) walked us through the reasoning behind boosters. Why do we need them? She shared that our current vaccines work really well (still, thankfully) against severe disease requiring hospitalization or resulting in death, even with the Delta variant. However, vaccine efficacy seems to be waning over time. Cue the need for boosters.


This data was fascinating to me. Israel mounted an aggressive vaccination campaign at the end of 2020 during a surge in cases despite having an already high vaccination coverage. As a reminder, Israel was one of the first countries to dramatically increase their vaccinations. Check out the % coverage by February - well done, Israel!

Then June hit with Delta and a surge happened.

There was also evidence of waning immunity among fully vaccinated folks across all age groups. Of note, they found waning immunity against severe disease among older adults (60+) and younger adults (40-49) (data not shown in the slide below but is in the full FDA hearing at 2:24:52).

Because of the surge, they mounted another vaccination campaign to introduce a booster dose. And the data is striking (well, at least to an epidemiologist).

This data is from a cohort of over 1.1 million people who were fully vaccinated with 2 doses of the Pfizer mRNA vaccine. Of those, some received a 3rd dose booster while others did not receive a booster.

The Big Takeaway - The 3rd dose of vaccination increased the protection against COVID-19 by 11.3 times and the protection against severe COVID-19 by 19.5 times. Whoa! The safety data from Israel also matched what I’ll discuss with the US data below.


Pfizer then talked about their clinical trial, which included a 3rd shot of the same dose of the first two shots for 300 trial participants. In terms of side effects, they were similar to the side effects seen after the 2nd shot and were mild and resolved after a day or two.

The Pfizer clinical trial also looked at whether or not a booster significantly increased neutralizing antibodies. Among both age groups of 18-55 and 65-85, we see a good boost in neutralizing antibodies after the booster.


Then the discussion and voting time came - which was pretty fascinating and sciency. =) Questions on B/T cells were asked - these are different than our neutralizing antibodies and tell the full story of how our long-term immune systems work. Unfortunately, Pfizer did not release that info to us. Other questions about vaccine equity in low-income countries, more data being needed, and is there a middle-ground? I’m curious to see how this decision affects our global supply of vaccines. In other words, will production increase? Will more doses be donated to low-income countries with extremely low supply? We shall see. I don’t know but I sure hope these large vaccine companies continue to donate to COVAX, GAVI, etc.

At the end of the vote, the committee voted against the booster shot for the general public unless you are in the following groups:

-Age 65+

-Certain high-risk medical conditions

-Frontline workers, including healthcare and teachers. (This part is a bit fuzzy of who qualifies).

I really liked this summary from Dr. Francis Collins, head of the NIH, regarding the boosters.


Now, we go the CDC this week for a vote and further discussion of how boosters should be rolled out. These next few weeks will also be pretty big in terms of vaccines for children 5-11 (halleluyer) and I’m hoping we will hear from Moderna and J&J about their booster data. Whew, things move fast right now, friends. I’m thankful for that because Delta also moves fast.

Get those vaccines if you haven’t! Get your booster if you’re eligible. Have a great Monday,


***Also, as a quick reminder - I do not read comments on FB, Twitter, or Insta for these posts. I only read comments for paid subscribers here on Substack and always appreciate the dialogue and discussions in this community. Happy weekend!