Evaluation of T cell responses with the QuantiFERON SARS-CoV-2 assay in individuals with 3 doses of BNT162b2 vaccine, SARS-CoV-2 infection, or hybrid immunity

• Published in: Diagnostic microbiology and infectious disease 2023-07, Vol.106 (3), p.115948-115948, Article 115948
• Main Authors: Dourdouna, Maria-Myrto, Tatsi, Elizabeth-Barbara, Syriopoulou, Vasiliki, Michos, Athanasios
• Format: Article
• Language: English
• Subjects: Adult; Antibodies, Viral; BNT162 Vaccine; cellular immunity; Child; COVID-19 - diagnosis; COVID-19 - prevention & control; COVID-19 Vaccines; Humans; Immunity, Humoral; interferon gamma release assay; mRNA vaccine; Original; QuantiFERON; SARS-CoV-2; T-Lymphocytes; Vaccination; Vaccines
• ISSN: 0732-8893; 1879-0070
• DOI: 10.1016/j.diagmicrobio.2023.115948

Cellular immunity after SARS-CoV-2 infection or immunization may be important for long-lasting protection against severe COVID-19 disease. We investigated cellular immune responses after SARS-CoV-2 infection and/or vaccination with an interferon-γ release assay (QuantiFERON, QFN), in parallel, with humoral immunity assessment. We recruited 41 participants: unvaccinated convalescent children and adults and vaccinated uninfected or vaccinated convalescent adults. All vaccinated adults had received three doses of the BNT162b2 COVID-19 vaccine at 6.2 to 10.9 months prior to their inclusion to the study. All the unvaccinated participants were tested negative with QFN. Regarding the vaccinated population, 50% (8/16) of the vaccinated uninfected adults and 57.1% (8/14) of the vaccinated convalescent adults were tested positive. QFN did not detect T cell responses in unvaccinated individuals and in a significant number of vaccinated individuals. Further comparative studies with different immunoassays are required to elucidate whether this is the result of waning immunity or low sensitivity of the assay.