evidence: We compared dynamics of the immune response after the third dose (administered ≥5 months after the second dose) with those after the second dose. We included 3972 HCWs who received the third dose and had at least 1 serological test 7 to 140 days after the third dose of vaccine; the number of participants who had tests at different times during the study is presented in Figure 1A. Results after the third dose were compared with those among a cohort of 4868 of the same HCWs who had serology testing after the second dose previously described.9 Serology samples were collected between January 21, 2021, and December 29, 2021. [...] Kinetics of SARS-COV-2 Cellular Immunogenicity After Third Vaccine Dose