T-cell response after first dose of BNT162b2 SARS-CoV-2 vaccine among healthcare workers with previous infection or cross-reactive immunity

• Published in: Clinical & translational immunology Vol. 10; no. 9; p. e1341
• Main Authors: Casado, Jose L, Haemmerle, Johannes, Vizcarra, Pilar, Rodriguez-Dominguez, Mario, Velasco, Tamara, Velasco, Hector, Centenera, Elena, Romero-Hernandez, Beatriz, Fernandez-Escribano, Marina, Vallejo, Alejandro
• Format: Journal Article
• Language: English
• Published: Australia John Wiley & Sons, Inc 01-01-2021; John Wiley and Sons Inc; Wiley
• Subjects: Antibodies; Antibody response; Cell-mediated immunity; cellular immunity; Coronaviruses; COVID-19; COVID-19 vaccines; cross‐reactivity; Humoral immunity; Immunoglobulin G; Infections; Lymphocytes; Lymphocytes T; Medical personnel; mRNA vaccine; mRNA vaccines; Nucleocapsids; Peptides; Proteins; SARS‐CoV‐2; Serology; Severe acute respiratory syndrome coronavirus 2; Short Communication; Vaccination; Vaccines; antibodies; COVID‐19; SARS‐CoV‐2; cellular immunity; cross‐reactivity; mRNA vaccine
• ISSN: 2050-0068; 2050-0068
• DOI: 10.1002/cti2.1341

Antibody response to the first dose of BNT162b2 SARS-CoV-2 is greater in COVID-19-convalescent than in infection-naïve individuals. However, there are no data about T-cell response in individuals with pre-existing cellular immunity.
We evaluated T-cell responses in parallel with SARS-CoV-2 antibody level after first dose of BNT162b2 vaccine in 23 infection-naïve and 27 convalescent healthcare workers (HCWs) previously included in a study about humoral and T-cell immunity.
Overall, the antibody response was lower in the infection-naïve group than in convalescent individuals (18 895 vs 662.7 AU mL
,
 < 0.001), and intermediate but significantly lower in convalescent HCWs with previous negative serology (25 174 vs 1793 AU mL
;
 = 0.015). Indeed, anti-spike IgG titres after the first dose correlated with baseline anti-nucleocapsid IgG titres (rho = 0.689;
 < 0.001). Pre-existing T-cell immunity was observed in 78% of convalescent and 65% of the infection-naïve HCWs. T-cell response after the first dose of the vaccine was observed in nearly all the cases with pre-existing T-cell immunity, reaching 94% in convalescent HCWs and 93% in those with cross-reactive T cells. It was lower in the infection-naïve group (50%;
 = 0.087) and in convalescent HCWs with negative serology (56%;
 = 0.085). Notably, systemic reactogenicity after vaccination was mainly observed in those with pre-existing T-cell immunity (
 = 0.051).
Here, we report that the first dose of BTN162b2 elicits a similar S-specific T-cell response in cases of either past infection or cross-reactive T cells, but lower in the rest of infection-naïve individuals and in convalescent HCWs who have lost detectable specific antibodies during follow-up.