Pfizer vaccine Booster reduces Covid 19 infection and severity across all Age Groups: NEJM

In a new study conducted by Yinon M and team, it was found that across all age groups studied, participants who received a booster dose of the BNT162b2 vaccine had significantly lower rates of confirmed Covid-19 and severe illness than those who did not.

The findings of this study were published in The New England Journal of Medicine on 8th December, 2021.

Following promising preliminary results from the administration of a third (booster) dose of the BNT162b2 messenger RNA vaccine (Pfizer–BioNTech) to individuals 60 years of age or older, the booster campaign in Israel was gradually expanded to include individuals in younger age groups who had received a second dose at least 5 months previously.

Researchers extracted data from the Israel Ministry of Health database on 4,696,865 people aged 16 and up who had received two doses of BNT162b2 at least 5 months prior for this study, which ran from July 30 to October 10, 2021. They compared the rates of confirmed coronavirus disease 2019 (Covid-19), severe illness, and death among those who had received a booster dose at least 12 days earlier (booster group) to those who had not received a booster (non-booster group). Rates in the booster group were compared to rates in those who had received a booster 3 to 7 days earlier in a secondary analysis (early post-booster group). After adjusting for potential confounding factors, Poisson regression models were used to estimate rate ratios.

The findings of this study are:

1. The rate of confirmed infection was lower in the booster group than in the non-booster group by about a factor of ten, and it was lower in the booster group than in the early post-booster group by a factor of 4.9 to 10.8.

2. In the primary analysis, the adjusted rate difference ranged from 57.0 to 89.5 infections per 100,000 person-days, and in the secondary analysis, it ranged from 34.4 to 38.3.

3. In the primary and secondary analyses, the rates of severe illness were lower in the booster group by a factor of 17.9 and 6.5, respectively, among those 60 years of age or older, and by a factor of 21.7 and 3.7, respectively, among those 40 to 59 years of age.

4. In the primary and secondary analyses, the adjusted rate difference was 5.4 and 1.9 cases of severe illness per 100,000 person-days among those 60 years of age or older, and 0.6 and 0.1 among those 40 to 59 years of age.

5. Mortality was reduced by a factor of 14.7 in the primary analysis and 4.9 in the secondary analysis among those aged 60 and up.

6. In the primary and secondary analyses, the adjusted rate difference was 2.1 and 0.8 deaths per 100,000 person-days, respectively.

In conclusion, the findings of this study provide evidence for the booster dose's short-term effectiveness against the currently dominant delta variant in people aged 16 and up. Future research will help determine the booster dose's long-term effectiveness against current and emerging variants.

Reference:

Protection against Covid-19 by BNT162b2 Booster across Age Groups., Yinon M. Bar-On, M.Sc., Yair Goldberg, Ph.D., Micha Mandel, Ph.D., Omri Bodenheimer, M.Sc., Laurence Freedman, Ph.D., Sharon Alroy-Preis, M.D., Nachman Ash, M.D., Amit Huppert, Ph.D., and Ron Milo, Ph.D. DOI: 10.1056/NEJMoa2115926