Anti-Spike Mucosal IgA Protection against SARS-CoV-2 Omicron Infection

nated, 0 to 13 days, 14 to 27 days, 1 to 2 months, 3 to 4 months, 5 to 6 months, 7 to 8 months, or ≥9 months).Among the patients who had received two doses of vaccine, waning of effectiveness against hospitalization was evident as early as 3 to 4 months after vaccination during both periods when the omicron sublineages were dominant.The vaccine effectiveness was 56.3% (95% confidence interval CI, 51.6 to 60.5) during the BA.1-BA.2wave and 47.4% (95% CI, 19.9 to 65.5) during the BA.4-BA.5 wave (Table 1).Although boosting with a third dose maintained vaccine effectiveness against severe disease caused by all four sublineages at 1 to 2 months, the vaccine effectiveness had decreased by 3 to 4 months to an effectiveness of 50.0%(95% CI, 4.4 to 73.9) during the BA.1-BA.2wave and 46.8% (95% CI, 35.3 to 56.2) during the BA.4-BA.5 wave.Thus, after either two doses or three doses of the BNT162b2 vaccine, we found rapid waning of vaccine effectiveness against the current sublineages of the omicron variant with respect to protection against hospitalization.Our data indicate that boosting maintains vaccine effectiveness against severe disease caused by the current omicron sublineages, although the evidence of rapid waning of durability indicates the need for regular boosting as early as 4 months after the last dose or the need for vaccines to incorporate variants of concern to maintain protection.