| dc.description.abstract | Background: Over the two years of the COVID-19 pandemic, the elderly in nursing
homes (NH) have been hit particularly hard.
Methods: We conducted a retrospective study of 3 episodes of COVID-19 in one NH in
suburban Belgrade, Serbia, at the time of pre-alpha (Nov 2020), delta (Nov 2021) and
omicron (Jan 2022) variants of SARS-CoV-2. All staff and 95% of residents were vaccinated
in the early spring of 2021, with BBIBP-CorV, Gam-COVID-Vac and BNT162b2
vaccines. COVID-19 was diagnosed by positive PCR and/or antigen test. Specific IgG
antibodies against SARS-CoV-2 S glycoprotein RBD were assessed by ELISA.
Results: The 3 episodes involved a total of 188 infections. The first involved 65/126
(51.9%) residents and 44/64 (68.7%) staff, the second 22/75 (29.3%) residents and 3/40
(7.5%) staff, and the third 36/110 (32.7%) residents and 18/56 (32.1%) staff. Clinical presentation
ranged from asymptomatic to severe, with severe cases being referred to
hospital ICUs. Mortality per episode was 19.8%, 2.7% and 0%, respectively, and involved
residents only. After the first episode, all 36 examined residents and 43 of the
44 staff had specific antibodies. Interestingly, higher levels (20.45±13.27) were detected
in the residents than in the staff (9.74±9.52) (p<0.001) despite a double difference
in age (79.6±7.48 vs. 40.8±11.43) (p<0.001). Episodes 2 and 3 involved 4 (1 resident, 3
staff) and 22 (13 residents, 9 staff) breakthrough infections.
Conclusions: Elderly individuals mounted a good immunological response to the
vaccines, which prevented significant mortality in the next episodes, despite a significant
number of omicron-induced breakthrough infections. | sr |
