Little is known about the factors associated with lack of T-cell response to mRNA vaccines against SARS-CoV-2. In a prospective cohort of 61 health care workers (HCWs), 21% and 16% after the first dose of mRNA BNT162b vaccine, and 12% and 7% after the second dose, showed lack of CD4+ and CD8+ T-cell response, respectively. Pre-existing T-cell immunity, due to past infection (46%) or cross-reactive cellular response (26%), was significantly associated with T-cell response in frequency (CD4+ T-cell, 100% vs 82% after two doses; p = 0.049) and in the magnitude of T-cell response during follow up. Furthermore, baseline CD4+ T-cell correlated positively with the titer of specific IgG-antibodies after first and second vaccine dose. Our data demonstrate that cross-reactive T-cells correlate with a better cellular response as well as an enhanced humoral response, and we confirm the close correlation of humoral and cellular response after mRNA vaccination.
Keywords: AU, arbitrary units; CLIA, chemoluminiscent immunoassay; COVID-19, Coronavirus disease 2019; Cellular response; IgG, immunoglobulin G; Pre-existing immunity; RT-PCR, retrotranscriptasepolymerase chain reaction; S protein, Spike protein; SARS-CoV-2 humoral response; SARS-CoV-2, Severe acute respiratory syndrome coronavirus 2; mRNA vaccine.
© 2022 The Author(s).