characteristics of the residents
In the seven NHs, non-vaccinated residents ranged from 3.9% to 32.6%, and RT-PCR-positive residents from 9.8% to 54.9%. Residents’ vaccination coverage was not significantly different across the NH sites (Table S 1). A total of 396 residents (57 to 103 years, mean ± sd: 87.33 ± 9.17 years), with 312 females (78.8%), were included. The Charlson comorbidity index ranged from 2 to 15 (median, percentiles: 6.0, 5.0-7.0). Fifty-one residents had prior-Covid-19, determined by a positive RT-PCR in 2020 or 2021, and only residents without prior positive RT-PCR had detectable N-protein-IgG in the blood collected for this study. There were 48 (12.2%) non-vaccinated residents, 31 (7.8%) with one vaccine dose, and 317 (80.0%) with two doses. Age, sex, Charlson co-morbidity index, or previous RT-PCR results were comparable in the groups (Table 1).
Blood sampling could not be performed in residents from NH number 4 (Table 1, Table S1, and Figure 1). In the 6 NHs in which a blood sample was offered, residents who were (N = 325) or were not (N = 25) sampled were similar in age, gender, and Charlson index (data not shown).