Booster doses effective

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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