PROS1 and infection: Furthermore, to elucidate whether long-term infection had or not an effect on the development of antigen-specific T cell responses, we took PBMCs at a DSSO corresponding to the first negative swab PCR result, corresponding to the convalescent phase, and stimulated them with a pool of peptides spanning the sequence of the S protein of the circulating variant of SARS-CoV-2 in Rio de Janeiro at the time of collection.