Spike-specific Cellular Immune Response After COVID-19 Vaccination

Aim of this study is to evaluate whether COVID-19 vaccination induces a persistent cellular immune response. To this aim, blood samples are taken from vaccinated individuals and not immunized subjects as a control group. Cells isolated from blood samples are tested in vitro to assess the percentage of spike-specific T and B lymphocytes 1 and 7 months after a second dose of Comirnaty vaccine.

After providing written informed consent, 28 vaccinated and 25 non vaccinated subjects were included in the study. All subjects were enrolled among healthcare workers in the Research Centre of IRCCS San Raffaele Roma in Rome. All the subjects declared that they never tested positive for COVID19. Blood and serum samples were drowned twice from vaccinated subjects: 1 and 7 months after a second dose of vaccine to evaluate T and B response to vaccine; blood was drowned once in not vaccinated subjects. Cells were collected form peripheral blood samples, while anti-S1 IgG titre was assessed in serum. Flow-cytometry was used to assess the percentage of circulating spike-specific T and B lymphocytes.