Abstract
Installing efficient protective immunity by anti-SARS-CoV-2 vaccines is the only current means to overcome coronavirus disease 2019 pandemics. The cellular and humoral immune responses induced with an messenger RNA (mRNA) (BNT162b2) or with a vector (ChAdOx1nCoV-19) vaccine among Bulgarian healthcare workers (n = 123, aged 23-71 years) were studied in the course of 16 weeks after priming. Receptor-binding domain (RBD)-blocking Abs and SARS-CoV-2 RBD immunoglobulin A (IgA) were evaluated in parallel with interferon gamma (IFNγ)-producing virus-specific T cells. Both vaccines induced RBD-blocking Abs in 100% of the participants after complete immunization while the levels of protection after a single dose largely varied (22%-98%). Advanced age had a negative impact on the level and longevity of virus-neutralizing activity induced by one dose mRNA, but not by the vector vaccine. RBD-binding IgA was detected in 100% of tested donors from the mRNA vaccine cohort, and in 67% of tested from the vector vaccine cohort, at least 1 month after completed immunization. One month after completing mRNA immunization, the number of IFNγ-producing T cells correlated significantly with the levels of RBD-specific IgA and virus-neutralizing activity induced after priming. Enumeration of circulating virus-specific IFNγ+ T cells is not recommended for evaluation of protective immunity as their detection may require longer stimulation beyond the firstmonth postimmunization. In conclusion, BNT162B2 and ChAdOx1nCoV-19 induced potent and comparable humoral and cellular anti-SARS-CoV-2 immune responses, peaking between 10 and 30 days after complete immunization. A single dose of any vaccine did not induce adequate protection in a great part of donors, making the shorter interval between mRNA vaccine doses preferable in the settings of increased risk of infection.
Keywords: COVID-19 vaccine; SARS-CoV-2 specific T-cell; immunity; virus-neutralizing antibody.
【저자키워드】 COVID-19 vaccine, Immunity, SARS-CoV-2 specific T-cell, virus-neutralizing antibody., 【초록키워드】 COVID-19, coronavirus disease, neutralizing antibody, SARS-CoV-2, Coronavirus disease 2019, Vaccine, COVID-19 vaccine, mRNA vaccine, T cells, Infection, immunization, healthcare worker, BNT162b2, Neutralizing activity, Cohort, T cell, Receptor-binding domain, Immunoglobulin, protective immunity, IgA, mRNA, immune responses, Pandemics, age, humoral immune response, donors, Longevity, immunoglobulin A, single dose, Donor, interferon gamma, cellular, dose, humoral, anti-SARS-CoV-2 vaccine, SARS-CoV-2 RBD, Messenger RNA, increased risk, IFNγ, advanced age, anti-SARS-CoV-2 immune responses, participant, priming, circulating, Complete, Enumeration, anti-SARS-CoV-2 vaccines, virus-neutralizing antibody, peaking, Course, tested, significantly, evaluated, overcome, correlated, induce, comparable, virus-neutralizing, Bulgarian, Installing, vaccine cohort, 【제목키워드】 COVID-19, Cellular immune response, prospective cohort study, healthcare worker, humoral, induction, Bulgarian,