Susceptibility to reinfection with SARS-CoV-2 virus relative to existing antibody concentrations and T cell response

Objectives: We investigated the reinfection rate of vaccinated or convalescent immunized SARS-CoV-2 in 952 expatriate workers with SARS-CoV-2 serological antibody (Ab) patterns and surrogate T cell memory at recruitment and follow-up. Methods: Trimeric spike, nucleocapsid, and neutralizing Abs were measured, along with a T cell stimu-lation assay, targeting SARS-CoV-2 memory in clusters of differentiation (CD) 4 + and CD8 + T cells. The subjects were then followed up for reinfection for up to 6 months. Results: The seroprevalence positivity at enrollment was greater than 99%. The T cell reactivity in this population was 38.2%. Of the 149 (15.9%) participants that were reinfected during the follow-up period (74.3%) had nonreactive T cells at enrollment. Those who had greater than 100 binding Ab units/ml in-crease from the median concentration of antispike immunoglobulin G Abs had a 6% reduction in the risk of infection. Those who were below the median concentration had a 78% greater risk of infection. Conclusion: Significant immune protection from reinfection was observed in those who retained T cell activation memory. Additional protection was observed when the antispike was greater than the median value.(c) 2023 The Author(s). Published by Elsevier Ltd on behalf of International Society for Infectious Diseases. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ )