Impaired CD4⁺ T Cell Response in Older Adults Is Associated with Reduced Immunogenicity and Reactogenicity of mRNA COVID-19 Vaccination

Using a vaccinated cohort (n = 216), researchers demonstrated that adults ≥65 years had fewer vaccine-induced spike-specific CD4+ T cells, including CXCR3+ circulating follicular helper T cells, and the TH1 subset of helper T cells after the first dose.