Study Design Summary: Multinational, placebo controlled trial of 43,448 patient’s who received either a 2 dose COVID-19 vaccine 21 days apart or placebo, with primary outcomes being safety and efficacy against lab confirmed COVID-19 infections.
Notes: The placebo and intervention arm were well balanced in their patient demographics, however, 83% of participants were white and countries such as Brazil and South Africa were included. Patients with HIV and other immune compromised states were included but the specific numbers and outcomes of these subgroups was not included in this paper. The trial did not included children under 16 or pregnant women. Participants reported symptoms of COVID with tested, there is no mention of routine testing, thus this study really only looks at symptomatic cases of COVID-19.
The study was designed as a 2 injection trial, with the doses 21 days apart. Among patients who had either no known COVID or evidence of COVID infection, COVID was contracted by 9 of the patients in the vaccine arm and 169 in the placebo arm, 0.04% vs 0.84%. Among patients with only no evidence of infection the cases with 8 in the vaccine arm and 162 in the placebo arm.
Interestingly, between the first and second doses of the vaccine the observed efficacy was 51%, and within 7 days of the second dose the efficacy was 91%, with the 95% efficacy being reach at 8 or more days after the second dose. The authors mention that there were 10 severe cases of COVID noted after the first dose and only 1 of those was in the vaccine arm, but no further details are provided.
Adverse events were similar between the placebo and intervention arm, there was more difference in the rate of adverse events after the second dose. The large majority of adverse events were mild to moderate and mainly pain at injection site, muscle aches, fatigue and headache. These adverse events were also more prevalent in the 16-55 year age range, but those over 55 years old had a larger delta increased percentage of patients experience these adverse events after the second dose as compared to after the first dose.
Study Conclusion: Pfizer’s COVID-19 vaccine is both safe and 95% effective at preventing COVID-19 infection.
Fusion Beat Bottom Line Impression: The Pfizer vaccine gives some local site reactions and flu-like symptoms, mainly after the second dose, as compared to placebo, but it is effective in reducing rates of symptomatic COVID-19 in white patients.
A Fusion Beat 