BNT162b2 vaccine booster dose protection: A nationwide study from Israel
https://www.gov.il/BlobFolder/reports...
Background
On July 30, 2021
Third (booster) dose of the Pfizer BNT162b2
Approved in Israel for 60 years or older, who had been fully vaccinated
At least five months previously
We estimate the reduction in relative risk for confirmed infection and severe COVID-19
Per person-days at risk
July 30 and August 22, 2021
Dynamic cohorts
Moved from ‘non-booster’ to join the ‘booster’ cohort 12 days later
No-booster cohort
4.0 million person- days
3,473 confirmed infections
330 cases of severe COVID-19
Booster cohort
3.4 million person-days
313 confirmed infections
32 cases of severe COVID-19
Twelve days or more after the booster dose we found
9.6 - 11.4 - 13.4 fold decrease in the relative risk of confirmed infection
9.5 - 15.5 fold decrease in the relative risk of severe illness
Discussion
If waning immunity to Delta is 50% protection against infection at more than 6 months
A booster - vaccinated individual susceptible to infection would decrease to 5% relative to unvaccinated
Therefore vaccine efficacy for booster-vaccinated individuals to 95%
(similar to the original “fresh” vaccine efficacy against the Alpha strain)
Our findings give clear indications of the effectiveness of a booster dose even against the currently dominant Delta variant
US and UK current thinking
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