Immune responses in Omicron SARS-CoV-2 breakthrough infection in vaccinated adults
Hassen Kared, Asia‐Sophia Wolf, Amin Alirezaylavasani, Anthony Ravussin, Guri Solum, Trung Tran, Fridtjof Lund‐Johansen, John Torgils Vaage, Lise Sofie Haug Nissen‐Meyer, Unni C. Nygaard, Olav Hungnes, Anna Hayman Robertson, Lisbeth Meyer Næss, Lill Trogstad, Per Magnus, Ludvig A. Munthe, Siri Mjaaland
Abstract
Abstract The SARS-CoV-2 Omicron variant has more than 15 mutations in the receptor binding domain of the Spike protein enabling increased transmissibility and viral escape from antibodies in vaccinated individuals. It is unclear how vaccine immunity protects against Omicron infection. Here we show that vaccinated participants at a super-spreader event have robust recall response of humoral and pre-existing cellular immunity induced by the vaccines, and an emergent de novo T cell response to non-Spike antigens. Individuals with Omicron SARS-CoV-2 breakthrough infections have significantly increased activated SARS-CoV-2 wild type Spike-specific cytotoxic T cells, activated follicular helper (T FH ) cells, functional T cell responses, boosted humoral responses, and rapid release of Spike and RBD-specific IgG + B cell plasmablasts and memory B cells into circulation. Omicron breakthrough infection affords significantly increased de novo memory T cell responses to non-Spike viral antigens. Concerted T and B cell responses may provide durable and broad immunity.