Longitudinal Evaluation of Severe Acute Respiratory Syndrome Coronavirus 2 T-Cell Immunity Over 2 Years Following Vaccination and Infection

2024

Background Within a year of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, vaccines inducing a robust humoral and cellular immune response were implemented worldwide. However, emergence of novel variants and waning vaccine-induced immunity led to implementation of additional vaccine boosters. Methods This prospective study evaluated the temporal profile of cellular and serological responses in a cohort of 639 SARS-CoV-2–vaccinated participants, of whom a large proportion experienced a SARS-CoV-2 infection. All participants were infection naïve at the time of their first vaccine dose. Proportions of SARS-CoV-2 spike–specific T cells were determined after each vaccine dose using the activation-induced marker assay, while levels of circulating SARS-CoV-2 antibodies were determined by the Meso Scale serology assay. Results We found a significant increase in SARS-CoV-2 spike–specific CD4+ and CD8+ T-cell responses following the third dose of a SARS-CoV-2 messenger RNA vaccine as well as enhanced CD8+ T-cell responses after the fourth dose. Furthermore, increased age was associated with a poorer response. Finally, we observed that SARS-CoV-2 infection boosts both the cellular and humoral immune response, relative to vaccine-induced immunity alone. Conclusions Our findings highlight the boosting effect on T-cell immunity of repeated vaccine administration. The combination of multiple vaccine doses and SARS-CoV-2 infections maintains population T-cell immunity, although with reduced levels in the elderly.

Open access content. Open access content
info:eu-repo/semantics/openAccess

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1479133463

UNIV OF COPENHAGEN
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