Patalon T, Gazit S, Pitzer VE, et al. - Evidence indicates waning immunity of the mRNA vaccine BNT162b2 (Pfizer-BioNTech), due to which Israel initiated a nationwide third-dose (booster) vaccination campaign during August 2021. In this case-control study, the initial short-term additional benefit of a 3-dose vs a 2-dose regimen was evaluated against infection of SARS-CoV-2.

• Included were 306,710 Israeli adults 40 years and older.

• Receiving the booster was linked with an estimated significant reduction in the odds of SARS-CoV-2 infection within a few weeks compared with receiving just the 2 primary doses.

• Odds of hospitalization were also lower for those receiving the booster.

• Overall a third dose appears to counteract the waning of vaccine-induced protection against SARS-CoV-2 infection in the short-term; further monitoring is required to determine the duration of immunity following the booster.