Was it this study (now in review)?
https://www.medrxiv.org/content/10.1101/2021.08.27.21262679v1
Background: On July 30, 2021, a third (booster) dose of the Pfizer BNT162b2 vaccine was
approved in Israel for individuals 60 years or older who had been fully vaccinated (i.e., received
two doses) at least five months previously. Here, we estimate the reduction in relative risk for
confirmed infection and severe COVID-19 provided by the booster dose.
Methods: 1,144,690 individuals aged 60y and older who were eligible for a booster dose were
followed between July 30 and August 22, 2021. We defined dynamic cohorts where individuals
initially belong to the ‘non-booster’ cohort, leave it when receiving the booster dose and join
the ‘booster’ cohort 12 days later. Rates of infection and severe COVID-19 outcomes per
person-days at risk were compared between the cohorts using Poisson regression, adjusting
for possible confounding factors.
Results: Twelve days or more after the booster dose we found an 11.4-fold (95% CI: [10.0,
12.9]) decrease in the relative risk of confirmed infection, and a >10-fold decrease in the
relative risk of severe illness. Under a conservative sensitivity analysis, we find ≈5-fold
protection against confirmed infection.
Conclusions: In conjunction with safety reports, this study demonstrates the effectiveness of a
third vaccine dose in both reducing transmission and severe disease and indicates the great
potential of curtailing the Delta variant resurgence by administering booster shots.
Curious about the word "relapsed". Was that an auto-correct goof? If not, what did you mean when you said "Israel relapsed a study"?