Pfizer–BioNTech COVID-19 vaccine
Pfizer and BioNTech announce BNT162b2's final Phase 3 efficacy analysis
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Original prompt & settings (JSON) ↗The 95% headline came from a stark split: 162 symptomatic cases among placebo recipients, 8 among the vaccinated. And "final analysis" did not mean the trial was finished.
18 November 2020: the primary endpoint reported
Pfizer and BioNTech announced on 18 November 2020 that the protocol-specified final efficacy analysis of their ongoing Phase 3 trial of BNT162b2 had met all primary efficacy endpoints.
The analysis counted 170 symptomatic COVID-19 cases: 162 among placebo recipients and 8 among vaccine recipients, corresponding to 95% efficacy from seven days after the second dose. Ten severe cases had occurred — nine in the placebo group, one in the vaccinated group.
What "final" and "95%" actually covered
"Final" meant the protocol-specified primary endpoint analysis, not the end of the trial or of participant follow-up. Enrollment stood at 43,661, of whom 41,135 had received a second dose by 13 November.
The 95% was trial efficacy against symptomatic COVID-19 under the study's case definition. It did not establish 95% prevention of infection, transmission, hospitalization or death, and ten severe cases were too few to carry claims about preventing deaths.
Filed with the FDA two days later
The companies said the FDA's required safety-data milestone had been reached and that the monitoring committee had reported no serious vaccine-related safety concerns — which is not a claim of no adverse events. The release itself disclosed severe solicited reactions, fatigue at 3.8% and headache at 2.0% after dose two.
Nothing was authorized on 18 November. Pfizer filed its U.S. emergency-use request on 20 November, and the peer-reviewed trial report followed in the New England Journal of Medicine on 10 December.
Sources
Researched 23 Aug 2026 5 sources 2 audit passes
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What the sources leave uncertain
- The date of the announcement is firm.
- “Final efficacy analysis” meant the protocol-specified primary endpoint analysis, not that the clinical trial or participant follow-up had ended.
- The reported 95% was trial efficacy against symptomatic COVID-19 under the study definition, not an all-purpose real-world “effectiveness rate.”
- On 18 November the evidence was presented in a company release; the peer-reviewed trial report followed in the New England Journal of Medicine on 10 December.