COVID vaccine-elicited T cells provide robust protection against OmicronTwo studies yesterday in Nature show that the Johnson & Johnson (J&J) and Pfizer/BioNTech COVID-19 vaccines provide robust cellular protection against serious illness caused by the highly transmissible Omicron (B.1.1.529) variant, despite evidence of waning neutralizing antibody protection against the virus.In one study, University of Cape Town researchers in South Africa evaluated the ability of vaccine-elicited T cells to react with Omicron's spike protein in vaccine recipients and in unvaccinated COVID-19 survivors.Among the 70 participants, 70% to 80% of the CD4+ and CD8+ T-cell response to Omicron was maintained across all three study groups.
The concentrations of Omicron cross-reactive T cells were similar to those against the Beta (B1351) and Delta (B1617.2) variants, even though Omicron is considerably more mutated.Among the 19 hospitalized patients infected with Omicron, T-cell responses to the variant's spike, nucleocapsid, and membrane proteins were comparable to the 49 patients hospitalized in previous pandemic waves in which the wild-type, Beta, or Delta variants were dominant."The extent to which other components of the adaptive response such as T cells may still target Omicron and contribute to protection from severe outcomes is unknown," the researchers wrote.The other study, by Beth Israel Deaconess Medical Center (BIDMC) researchers, evaluated both cellular and antibody immune response in 47 COVID-19 vaccine recipients 1 and 8 months after vaccination.Among COVID-19 vaccine recipients, median Omicron spike-specific CD8+ T-cell responses were durable and were 82% to 84% of those elicited by the wild-type virus.