A Pfizer-funded study by S.Y. Tartof et al titled “Effectiveness of mRNA BNT162b2 COVID-19 vaccine up to 6 months in a large integrated health system in the USA: a retrospective cohort study” was published on October 4. The study period was from 14 December 2020 to 8 August 2021. It included over 3.4 million individuals.
Over the entire study period, fully vaccinated individuals had an adjusted vaccine effectiveness of 73% (95% CI 72–74) against SARS-CoV-2 infections and 90% (89–92) against COVID-19-related hospital admissions (appendix pp 6–7).
That is more-or-less expected but the effectiveness against infection “for the fully vaccinated decreased with increasing time since vaccination, declining from 88% (95% CI 86–89) during the first month after full vaccination to 47% (43–51) after 5 months”.
The effectiveness against hospital admissions remained at 87% to 88% during the study period.
As for the other variants, effectiveness against infection was high at 93% after 1 month of vaccination before dropping significantly.
At 4 months after full vaccination, vaccine effectiveness against delta infections declined to 53% (95% CI 39–65) and vaccine effectiveness against other variants declined to 67% (45–80; p=0·25).
So, the only positive note from this study is that it seems to be effective against hospitalizations for at least 5 months. However, that says nothing about long-term safety or transmissivity if one happens to be infected even if not hospitalized.
Be sure to subscribe to our mailing list so you get each new Opinyun that comes out!
Comments