A large study of booster efficacy was conducted by the Maccabi Healthcare Services in Israel to determine the efficacy of a 3rd booster shot. They found that a third dose of the mRNA vaccine BNT162b2 (Pfizer BioNTech) provided additional protection against detected SARS-CoV-2 infection according to a release from PubMed.
They estimated an 83% to 87% reduction in the odds of testing positive for SARS-CoV-2 after at least 2 weeks following receipt of the booster compared with receiving 2 doses. This reduction comes on top of the reduction in the risk conferred by the first 2 doses. This analysis also suggests that individuals who received the booster dose have lower odds of hospitalization than those receiving 2 doses.
With the evidence of waning immunity of the mRNA vaccine BNT162b2 (Pfizer-BioNTech), a nationwide third-dose (booster) vaccination campaign was initiated in Israel during August 2021; other countries have begun to administer a booster shot as well.
