Protein vaccine NVX-CoV2373 elicits functional T cell immunity

Abstract

The SARS-CoV-2 vaccine NVX-CoV2373 is a protein-based vaccine that might circumvent the difficulties in distributing mRNA vaccines to regions with limited access to cold-chain and refrigeration. However, the NVX-CoV2373-induced T cell and antibody responses remain poorly understood. In this issue of the JCI, Moderbacher et al. characterized SARS-CoV-2-specific CD4+ and CD8+ T cell responses elicited by one or two doses of NVX-CoV2373 in individuals enrolled in a phase I/IIa trial. Substantially increased spike-specific CD4+ and T follicular helper cells were found after the first or second vaccine dose, with some individuals developing a modest spike-specific CD8+ T cell response. Correlation analysis revealed an association between spike-specific CD4+ T cells and neutralizing antibody titers. Notably, preexisting T cell immunity showed negligible effects on NVX-CoV2373-induced T cell responses. These findings indicate that the protein-based vaccine NVX-CoV2373 induces robust T cell immunity capable of recognizing SARS-CoV-2 antigens and supporting humoral immune responses.

Figure 1. T cell immune response in individuals who received NVX-CoV2373 vaccine.

Individuals who received one or two doses of the protein-based NVX-CoV2373 vaccine exhibited increased levels of SARS-CoV-2 spike–specific CD4⁺ T cells, circulating Tfh cells, CD8⁺ T cells, and serum neutralizing antibodies. Spike-specific CD4⁺ T cell frequency correlated with the SARS-CoV-2–neutralizing antibody titers. Spike-specific CD4⁺ T cell response was present in most of the individuals who received one or two doses of NVX-CoV2373 vaccine, while a smaller proportion of vaccinees displayed spike-specific circulating Tfh cells and spike-specific CD8⁺ T cells.