Results
SARS-CoV-2 infection, infections
MAY, SARS-COV-2 INFECTION, INFECTIONS
From Nov 12, 2021, to Jan 27, 2022, we screened 994 individuals, and 818 (82%) passed the initial eligibility assessment (We collected information on post-vaccination reactions in 424 (94%) of 451 participants, including 193 (46%) of 424 who reported ever feeling unwell after vaccination, with significantly more frequent reactions in recipients of a third dose of BNT162b2 that mostly subsided within 7 days (We measured sera neutralising antibodies from third-dose vaccination in 435 participants who provided paired day 0 and day 28 sera after vaccination (In a random subset of 20 participants from each group (Data on SARS-CoV-2 infection from 378 (84%) of 451 participants were analysed, including 85 (84%) of 101 in the CC-C group, 104 (88%) of 118 in the CC-B group, 96 (81%) of 118 in the BB-C group, and 93 (82%) of 114 in the BB-B group. After receiving third-dose vaccination, and before active surveillance started, 42 infections were identified either by rapid antigen test or PCR, including in ten participants in the CC-C group, 11 in the CC-B group, 11 in the BB-C group, and ten in the BB-B group. During active surveillance from March 11 to May 31, 2022, participants reported a rapid antigen test result, on average, every 4·5 days for a median of 69 days (IQR 60–76). 24 infections were identified either by systematic rapid antigen test or self-reported PCR, including three participants in the CC-C group, eight in the CC-B group, five in the BB-C group, and eight in the BB-B group. A daily symptom diary was initiated for 53 illness episodes from 52 participants, from which 22 infections were identified by rapid antigen test or PCR, including three participants in the CC-C group, nine in the CC-B group, three in the BB-C group, and seven in the BB-B group. Together, we identified 58 SARS-CoV-2 infections by May 31, 2022 (