Long-term adaptive response in COVID-19 vaccine recipients and the effect of a booster dose

• Published in: Frontiers in immunology Vol. 14; p. 1123158
• Main Authors: Perico, Luca, Todeschini, Marta, Casiraghi, Federica, Mister, Marilena, Pezzotta, Anna, Peracchi, Tobia, Tomasoni, Susanna, Trionfini, Piera, Benigni, Ariela, Remuzzi, Giuseppe
• Format: Journal Article
• Language: English
• Published: Switzerland Frontiers Media S.A 28.02.2023
• Subjects: Antibodies, Neutralizing; COVID-19; COVID-19 - prevention & control; COVID-19 Vaccines; Delta; Humans; Immunology; mRNA vaccine; neutralizing antibodies; Omicron; RNA, Viral; SARS-CoV-2; COVID-19; SARS-CoV-2; Delta; neutralizing antibodies; Omicron; T and B cells; mRNA vaccine
• ISSN: 1664-3224; 1664-3224
• DOI: 10.3389/fimmu.2023.1123158

We examined the immune response in subjects previously infected with SARS-CoV2 and infection-naïve 9 months after primary 2-dose COVID-19 mRNA vaccination and 3 months after the booster dose in a longitudinal cohort of healthcare workers. Nine months after primary vaccination, previously infected subjects exhibited higher residual antibody levels, with significant neutralizing activity against distinct variants compared to infection-naïve subjects. The higher humoral response was associated with higher levels of receptor binding domain (RBD)-specific IgG + and IgA + memory B cells. The booster dose increased neither neutralizing activity, nor the B and T cell frequencies. Conversely, infection-naïve subjects needed the booster to achieve comparable levels of neutralizing antibodies as those found in previously infected subjects after primary vaccination. The neutralizing titer correlated with anti-RBD IFNγ producing T cells, in the face of sustained B cell response. Notably, pre-pandemic samples showed high Omicron cross-reactivity. These data show the importance of the booster dose in reinforcing immunological memory and increasing circulating antibodies in infection-naïve subjects.