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).