Abstract
Effective vaccination is a key element in the exit strategy from the current severe acute respiratory syndrome-CoV coronavirus-2 (SARS-CoV-2) pandemic, and may also offer protection against severe disease from future variants of concern. Here, we prospectively monitored T-cell responses over time, using ELISpot interferon-γ (INF-y) release assays, and B-cell responses, using serological tests, after vaccination and booster with BioNTech/Pfizer mRNA (Pfizer) and Janssen vector (Janssen/Johnson & Johnson) vaccines in hospital health care workers. Vaccine recipients were divided into seropositive and seronegative individuals at baseline, in order to determine the effect of natural immunity on vaccine-induced immune kinetics. We found that convalescent individuals mounted higher spike-specific INF-y-secreting T-cell responses and B-cell-mediated IgG responses, after receiving the Janssen vaccine or the first dose of the Pfizer vaccine. IgG levels corresponded to the virus neutralization capacity as measured by VNT assay. At 8 months postvaccination, spike-specific cellular immunity waned to low levels in individuals with or without prior natural immunity, whereas waning of humoral immunity occurred predominantly in naive individuals. The booster shot effectively reinduced both cellular and humoral immune responses. To conclude, our data supports the implemented single-dose mRNA booster strategy employed in the Netherlands. Furthermore, the level of pre-existing natural immunity may be factored into determining the optimal time window between future booster vaccines.
Keywords: ELISA; ELISpot IFN-γ release assay; SARS-CoV-2; T-cell response; mRNA vaccine; vector vaccine.
【저자키워드】 SARS-CoV-2, mRNA vaccine, T-cell Response, ELISA, vector vaccine., ELISpot IFN-γ release assay, 【초록키워드】 Vaccine, vaccination, pandemic, hospital, health care workers, variants of concern, immune, Pfizer, Humoral immunity, mRNA, Virus neutralization, ELISPOT, T-cell, humoral immune responses, serological, seropositive, seronegative, booster, IFN-γ, booster vaccines, B-cell, janssen, Coronavirus-2, cellular, natural immunity, severe disease, Netherlands, IgG responses, Support, interferon-γ, first dose, individual, recipient, offer, postvaccination, VNT, responses, spike-specific cellular immunity, convalescent individual, occurred, assays, receiving, determine, individuals, baseline, IgG level, mounted, waned, 【제목키워드】 Cellular immune response, Health care worker, convalescent, humoral,