Protection Across Age Groups of BNT162b2 Vaccine Booster against Covid-19

Bar-On, Y. M.; Goldberg, Y.; Mandel, M.; Bodenheimer, O.; Freedman, L.; Alroy-Preis, S.; Ash, N.; Huppert, A.; Milo, R.

BACKGROUND Following administration to persons 60+ years of age, the booster vaccination campaign in Israel was gradually expanded to younger age groups who received a second dose >5 months earlier. We study the booster effect on COVID-19 outcomes. METHODS We extracted data for the period July 30, 2021 to October 5, 2021 from the Israeli Ministry of Health database regarding 4,616,994 persons. We compared confirmed Covid-19 infections, severe illness, and death of those who received a booster [≥]12 days earlier (booster group) with a nonbooster group. In a secondary analysis, we compared the rates 3-7 days with [≥]12 days after receiving the booster dose. We used Poisson regressions to estimate rate ratios after adjusting for possible confounding factors. RESULTS Confirmed infection rates were {approx}10-fold lower in the booster versus nonbooster group (ranging 8.8-17.8 across five age groups) and 4.7-11.4 fold lower in the secondary analysis. Severe illness rates in the primary and secondary analysis were 19.1-fold (95% CI, 15.9-23) and 6.5-fold (95% CI, 5.1-8.4) lower for ages 60+, and 20.7-fold (95% CI, 9.7-44.2) and 2.9-fold (95% CI, 1-8.8) lower for ages 40-60. For ages 60+, COVID-19 associated death rates were 13.9-fold (95% CI, 8.8-22) lower in the primary analysis and 4.6-fold (95% CI, 2.7-7.9) lower in the secondary analysis. CONCLUSIONS Across all age groups, rates of confirmed infection and severe illness were substantially lower among those who received a booster dose of the BNT162b2 vaccine.