Time from last immunity event against infection during Omicron-dominant period in Malaysia.

Objectives: To study the incidence of Omicron infections in Malaysia and the exposures that could reduce the hazard of attaining Omicron infection.

Methods: We used a multicenter, prospective cohort to study 482 healthcare workers vaccinated with two and three doses of BNT162b2 for SARS-CoV-2 infection during the Omicron-dominant period in Malaysia.

Results: Between January 31 and July 31, 2022, the cumulative incidence was 44.

COVID-19 breakthrough infections and humoral immune response among BNT162b2 vaccinated healthcare workers in Malaysia.

The evaluation of breakthrough infection and humoral immunity responses are important outcomes for vaccination policy for healthcare staff. This prospective cohort study collected blood samples at 5-time points; before primary vaccine doses, and at 2, 10 and 24 weeks after BNT162b2 vaccination from 551 HCWs, between March and October 2021. We investigated the association between anti-spike-1 protein receptor-binding domain (anti-S1-RBD) antibody geometric mean titre (GMT) and breakthrough infections.