Pfizer Vaccine Data Before FDA Panel

March 31, 2021
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New analysis on the first COVID-19 vaccine considered for Emergency Use Authorization by the FDA.

Here’s what we know.

What It Is:

  • A two-dose Pfizer-BioNTech vaccine.
  • Developed using messenger RNA technology (mRNA); gives the body a genetic blueprint to build a viral protein in order to teach the body what to later identify and protect against.
  • Commonly called “the Pfizer vaccine,” though development started in early January by the founders of a German company, BioNTech, who feared COVID-19 would spread worldwide.

Does It Work?

Based on analysis released by the FDA:

  • Early data suggests benefits after first dose and 95% efficacy of preventing COVID-19 after two doses.
  • “…suggested benefit of the vaccine in preventing severe COVID-19, in preventing COVID-19 following the first dose, and in preventing COVID-19 in individuals with prior SARS-CoV-2 infection…”

Who Was Tested:

  • 44,000 participants overall.
  • Ages range from 12 to 75 yrs old & up.
  • Participants during Stage 1 “excluded participants at high risk of SARS-CoV-2 infections.”
  • Phase 2/3 expanded to those higher risk, with preexisting conditions such as obesity and diabetes.
  • Phase 2/3 ratio of men:women was nearly even. Most participants (82%) were white. Median age: 51.


“….no specific safety concerns identified that would preclude issuance of an EUA.”

Data was gleaned from approx. 38,000 participants 16 years & older over a median follow-up duration of two months after their second dose.

What Reactions Did People Commonly Have?

  • injection site reactions (84.1%);
  • fatigue (62.9%);
  • headache (55.1%);
  • muscle pain (38.3%);
  • chills (31.9%);
  • joint pain (23.6%);
  • fever (14.2%).

*Reactions were more prevalent in younger participants, rather than older.*


“Pregnancy outcomes are otherwise unknown at this time.”

  • Women were given pregnancy tests before participating in trial and excluded if pregnant.
  • 23 pregnancies occurred during trial (12 in women who received the vaccine, 11 in placebo group) and the study will be “collecting outcomes” of these pregnancies.

The mRNA technology used to create this vaccine has never been approved for use against infectious diseases or licensed in the United States — for emergency use authorization (EUA) or otherwise. An advisory panel will recommend whether or not to grant EUA to this vaccine on Thursday Dec. 10.

**Update** the panel voted to recommend emergency use authorization of this vaccine.

Here’s a rough outline of where we gathered our info:

Card 3: Page 6

Card 4: 12/19

Card 5: Page 6

Card 6: Page 6

Card 7: 42

by Jenna Lee,