According to Israeli prospective data published in the journal JAMA Internal Medicine despite having a less potent anti-infection impact, a fourth dosage, or second booster, of Pfizer/COVID-19 BioNTech′s vaccine (Comirnaty), benefited elderly patients in long-term care and protected them from the worst outcomes during the Omicron wave.

The effectiveness of a fourth dose among almost 40,000 inhabitants (compared to a third given at least 4 months earlier) was 64% and 67% against hospitalizations for mild/moderate or severe illness, respectively, and 72% against COVID-19-related mortality.

The study′s findings came from 43,775 long-term facility residents in Israel, of whom 55 % had received a fourth dose of the Pfizer vaccination and 45 % had only had a third dose at least four months earlier. Over two thirds of the study′s participants were women, with an average age of 80. About 60% of them were residing in senior housing. The follow-up was on average 73 days. SARS-CoV-2 infection was found in 4058 fourth-dose recipients and 4370 third-dose recipients more than 7 days after receiving the fourth dosage of the vaccine (cumulative incidence, 17.6 % vs 24.9 %). The hospitalization occurrences for mild-to-moderate COVID-19, severe illness, and fatality were 0.9 % and 2.8 %, 0.5 % and 1.5 %, and 0.2% and 0.5%, respectively. 

The study concluded that there may be a significant correlation between receiving a fourth BNT162b2 dose and a reduced risk of COVID-19-related hospitalizations, serious illness, and fatalities during the Omicron surge. Additionally, the study also found that elderly inhabitants of long-term care facilities (LTCF) had a modest level of protection against SARS-CoV-2 infection overall. (MedPage Today June 23, 2022)