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Review 1: "Protection Across Age Groups of BNT162b2 Vaccine Booster against Covid-19"

This paper claims that compared to people who only received two doses of the Pfizer vaccine, those who additionally received the booster dose are less likely to have SARS CoV 2 infection, severe illness, and death. Both reviewers agree on the robustness of the study methods.

Published onNov 06, 2021
Review 1: "Protection Across Age Groups of BNT162b2 Vaccine Booster against Covid-19"
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key-enterThis Pub is a Review of
Protection Across Age Groups of BNT162b2 Vaccine Booster against Covid-19

AbstractBACKGROUNDFollowing 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.METHODSWe extracted data for the period July 30, 2021 to October 6, 2021 from the Israeli Ministry of Health database regarding 4,621,836 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.RESULTSConfirmed infection rates were ≈10-fold lower in the booster versus nonbooster group (ranging 8.8-17.6 across five age groups) and 4.8-11.2 fold lower in the secondary analysis. Severe illness rates in the primary and secondary analysis were 18.7-fold (95% CI, 15.7-22.4) and 6.5-fold (95% CI, 5.1-8.3) lower for ages 60+, and 22.0-fold (95% CI, 10.3-47.0) and 3.2-fold (95% CI, 1.1-9.6) lower for ages 40-60. For ages 60+, COVID-19 associated death rates were 14.7-fold (95% CI, 9.4-23.1) lower in the primary analysis and 4.8-fold (95% CI, 2.8-8.2) lower in the secondary analysis.CONCLUSIONSAcross all age groups, rates of confirmed infection and severe illness were substantially lower among those who received a booster dose of the BNT162b2 vaccine.

RR:C19 Evidence Scale rating by reviewer:

  • Strong. The main study claims are very well-justified by the data and analytic methods used. There is little room for doubt that the study produced has very similar results and conclusions as compared with the hypothetical ideal study. The study’s main claims should be considered conclusive and actionable without reservation.



This study by investigators in Israel assessed the effect of booster doses of the BNT162b2 COVID-19 vaccine on the rate of COVID-19 illnesses and deaths in a large observational cohort study. The results provide compelling evidence supporting the effectiveness of booster doses in individuals across the age spectrum, beginning 12+ days following the receipt of the booster dose. While the authors did not calculate the effectiveness of booster doses, the reductions in the rate of important COVID-19 outcomes are consistent with a very high level of vaccine booster dose effectiveness. Unfortunately, the study was unable to provide estimates of the impact of booster doses among finer gradients of age above 60 years, presumably because of small numbers of individuals. Additionally, the manuscript could not provide estimates of the impact of booster doses on individuals with immuno-compromising or other underlying illnesses, presumably because this information was unavailable to the investigators. Although it is difficult to exclude the effect of confounding and various forms of selection and information bias on the results entirely, the study provides strong evidence that booster doses of the BNT162b2 vaccine have their intended effect.

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