Twelve months after the first SARS-CoV-2 cases in Wuhan, the FDA approved the first COVID-19 vaccine (Pfizer-BioNTech). Early studies on healthcare workers showed that antibody levels, especially against the Spike protein, declined within six months, particularly in those without prior infection. However, previously infected individuals had stronger and longer-lasting responses. The vaccine induces a Th1-type T cell response, linked to milder disease, and activates follicular helper T cells and B cell responses, although antibody levels drop over time. Immune responses also differ by sex, with females showing stronger humoral responses. Key priorities include understanding humoral fluctuations, characterizing cellular immunity, and correlating both responses.
Study Type
OBSERVATIONAL
Enrollment
127
The evaluation of the T cell response will be performed by quantifying the frequencies of SARS-CoV-2-specific T cells producing IFN-γ using an enzyme-linked immunospot assay (ELISpot), with cryopreserved PBMC collected at the designated timepoints (T0, T1, T2, T3, and T4)
IRCCS Ospedale San Raffaele
Milan, Italy, Italy
To assess the existence of a correlation between the antibody titer six months after the second dose and the T and B cell responses
Correlation between antibody titer, in terms of antibodies directed against the Spike protein, and T cell response, in terms of IFN-γ measured by ELISpot, as well as B cell response, in terms of frequency and phenotype, assessed six months after the second dose (T3)
Time frame: Six months after the second vaccine dose, which coincides with the time of enrollment
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