SARS-CoV-2 Omicron infections are common among individuals who are vaccinated or have recovered from prior variant infection, but few reports have immunologically assessed serial Omicron infections. We characterized SARS-CoV-2 humoral responses in an individual who acquired laboratory-confirmed Omicron BA.1.15 ten weeks after a third dose of BNT162b2, and BA.2 thirteen weeks later. Responses were compared to 124 COVID-19-naive vaccinees. One month post-second and -third vaccine doses, the participant's wild-type and BA.1-specific IgG, ACE2-displacement and virus neutralization activities were average for a COVID-19-naive triple-vaccinated individual. BA.1 infection boosted the participant's responses to the cohort ≥95th percentile, but even this strong "hybrid" immunity failed to protect against BA.2. Reinfection increased BA.1 and BA.2-specific responses only modestly. Though vaccines clearly protect against severe disease, results highlight the continued importance of maintaining additional protective measures to counteract the immune-evasive Omicron variant, particularly as vaccine-induced immune responses naturally decline over time.
Keywords: COVID-19; Omicron variant; humoral immunity; reinfection; vaccine.
Copyright © 2022 Lapointe, Mwimanzi, Cheung, Sang, Yaseen, Kalikawe, Datwani, Waterworth, Umviligihozo, Ennis, Young, Dong, Kirkby, Burns, Leung, Holmes, DeMarco, Simons, Matic, Montaner, Brumme, Prystajecky, Niikura, Lowe, Romney, Brockman and Brumme.