Methodological Analysis: Randomized Controlled Trials for Pfizer and Moderna COVID-19 Vaccines.
Donna Hallas, Regena Spratling, Jason Fletcher
PMID 34243845WHAT IT FOUND
The appraised Pfizer and Moderna vaccine trials reported 95% and 94.1% efficacy against symptomatic infection, and severe cases were rare in vaccine groups.
Follow-up was short.
Key findings
01In the appraised trials, Pfizer reported 95% protection after dose 2 and Moderna reported 94.1% efficacy against symptomatic illness.
02In the Pfizer trial, severe cases after the first dose were one in vaccine and nine in placebo; in Moderna, all 30 severe cases were in placebo.
03The appraisal found both trials mostly rigorous but noted gaps: Pfizer participants from South Africa were not clearly accounted for, and Moderna pharmacists and vaccine administrators were not blinded.
STILL TO COME
How it was doneWhat they foundWhat it means for RNs
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What it does not show
This paper is an appraisal of two published trials, not a new trial, so it adds no direct patient outcomes. It reports efficacy under trial conditions, not effectiveness in usual care. Follow-up was short, and not all clinically important outcomes were considered. For Pfizer, accounting for South African participants was unclear, and HIV-positive participants were analyzed separately and not included. For Moderna, pharmacists and vaccine administrators knew assignments, although they had no other trial role. The CASP checklist used for appraisal did not cover vaccine-specific concerns such as side effects.
The easy way to misread this
Do not read the 95% and 94.1% figures as proof of real-world effectiveness or long-term safety. The paper appraises randomized trials that reported efficacy and says follow-up was short and not all clinically important outcomes were assessed.