By Mercedes Yanes Lane
Israel’s Ministry of Health used routine vaccine and COVID-19 surveillance to calculate the effectiveness of the Pfizer-BioNTech vaccine, seven days after the second injection. The results, in this The Lancet preprint, show that not only were high proportions of the population vaccinated (82.8% of people over 65 received two doses), but that vaccines were highly effective in preventing SARS-CoV-2 infections, translating to a steep decline in cases.
This preprint study, therefore not peer reviewed, carried out by the Ministry of Health and researchers from Pfizer, reports on the outcomes of the vaccinated population in Israel from January 2021 to March 2021. The Ministry of Health routinely collects information on vaccination, laboratory-confirmed SARS-CoV-2 infections, COVID-19 hospitalizations, and deaths due to COVID-19. This information allowed researchers to evaluate the effectiveness of two doses of the BNT162b2 vaccine (Pfizer-BioNTech), seven days after the last injection.
In total during the observation period, 3.3 million people (51.5% of the total population over 15 years of age) were vaccinated with two doses of BNT162b2. Among people 65 and older, 82.8% had received both doses. The overall effectiveness of the vaccine was 94.1% for preventing SARS-CoV-2 infections, 96.3% when looking at prevention of symptomatic infections, and 93.3% when looking at prevention of death. These estimates increased when looking at outcomes 14 days after the second dose.
The effect on the daily average of SARS-CoV-2 cases was also investigated and showed that cases steeply declined once high vaccine coverage was achieved. This was more evident among the elderly population in which vaccine coverage was highest. Such a drastic decline was not observed when public health measures, such as lockdown, where put in place, indicating the importance of vaccination as a control measure.
One of the main limitations that the authors discuss is that the testing policy for vaccinated and unvaccinated people differed. Vaccinated cases were exempt from testing after contact with a confirmed case or when returning from travel. This may underestimate the true number of infections among vaccinated people, especially of asymptomatic cases.
The authors conclude that two doses of the BNT162b2 vaccine appear to be highly effective in preventing confirmed SARS-CoV-2 infections as well as showing nationwide declines in the number of cases after mass vaccination.
Haas Eric J., Angulo Frederick J., McLaughlin John M., Anis Emilia, Singer Shepherd R., Khan Farid, Brooks Nati, Smaja Meir, Mircus Gabriel, Pan Kaijie, Southern Jo, Swerdlow David L., Jodar Luis, Levy Yeheskel, Alroy-Preis Sharon. Nationwide Vaccination Campaign with BNT162b2 in Israel Demonstrates High Vaccine Effectiveness and Marked Declines in Incidence of SARS-CoV-2 Infections and COVID-19 Cases, Hospitalizations, and Deaths. Available at SSRN: https://ssrn.com/abstract=3811387