Pfizer’s Data

We have questions about Pfizer’s COVID-19 vaccine data.

1) If there were only 10 severe cases of Covid out of 43,661, and one of those was vaccinated, why is the vaccine described as 94% effective rather than 90% effective, if the end point was to prevent hospitalization and severe outcome?

2) What reason is given for the ~21,000 placebo recipients who did NOT develop symptomatic COVID-19? What other strategies were they using in addition to the vaccine, and did those offer as much protection as the vaccine?

3) Given they had 41,135 trial participants receiving 2 doses of the vaccine; why is Pfizer’s FINAL analysis of reactogenicity data limited to ~8,000 participants?

4) Given they STARTED OUT with 43,661 total trial participants, then why did 2,526 choose NOT to get the second dose?

5) Given 41,135 of 43,661 were eventually given 2 doses of the vaccine (and how many got 1?) , how will Pfizer — or anyone — ever be able to compare long-term health outcomes between vaccinated and unvaccinated?

6) Exactly WHY and HOW does the vaccine cause severe headache in 2%? And how does this balance with “First, do no harm” when giving this to healthy individuals?

From Pfizer’s news release:
“There were 10 severe cases of COVID-19 observed in the trial, with nine of the cases occurring in the placebo group and one in the BNT162b2 vaccinated group.”

“A review of unblinded reactogenicity data from the final analysis which consisted of a randomized subset of at least 8,000 participants 18 years and older in the phase 2/3 study demonstrates that the vaccine was well tolerated, with most solicited adverse events resolving shortly after vaccination. The only Grade 3 (severe) solicited adverse events greater than or equal to 2% in frequency after the first or second dose was fatigue at 3.8% and headache at 2.0% following dose 2. Consistent with earlier shared results, older adults tended to report fewer and milder solicited adverse events following vaccination.”

“The Phase 3 clinical trial of BNT162b2 began on July 27 and has enrolled 43,661 participants to date, 41,135 of whom have received a second dose of the vaccine candidate as of November 13, 2020.”