Third-Dose BNT162b2 Vaccination Elicits Markedly High-Level SARS-CoV-2–Neutralizing Antibodies in Vaccinees Who Responded Poorly to a Second Dose in Japan

Abstract

To the editor—We read with great interest the article by Saciuk et al demonstrating that, in a retrospective cohort study in Israel, an additional dose of BNT162b2 vaccine 6 months after initial 2-dose vaccination bolsters protection against infection, with a vaccine effectiveness of 89%, as assessed during August–October 2021, when the majority of infections were due to the Delta variant [ 1]. Recent severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) studies using pseudovirus have shown that a third dose of BNT162b2 well elicits neutralizing antibodies against VOC (variants of concern) including Omicron (B.1.1.529, BA.1) [ 2–4]. However, Cheng et al very recently reported a single-source outbreak of Omicron BA.2 sublineage in Hong Kong, which indicates high transmissibility of Omicron/BA.2 [ 5] and poses further concerns on the efficacy of anti–SARS-CoV-2 vaccines.