Asymptomatic carriage rates and case-fatality of SARS-CoV-2 infection in residents and staff in Irish nursing homes

Kennelly, S. P.; Dyer, A. H.; Martin, R.; Kennelly, S. M.; Martin, A.; O'Neill, D.; Fallon, A.

Background: SARS-CoV-2 has disproportionately affected nursing home (NH) residents. In Ireland, the first NH case of COVID-19 occurred on 16/03/2020. A national point-prevalence testing program of all NH residents and staff took place from 18/04/2020-05/05/2020. Aims: To examine characteristics of NHs across three Community Health Organisations (CHOs) in Ireland, proportions with COVID-19 outbreaks, staff and resident, symptom-profile and resident case-fatality. Methods: Forty-five NHs surveyed across three CHOs requesting details on occupancy, size, COVID-19 outbreak, timing of outbreak, total symptomatic/asymptomatic cases, and outcomes for residents from 29/02/2020-22/05/2020. Results: Surveys were returned from (62.2%, 28/45) of NHs (2043 residents, 2303 beds). Three-quarters (21/28) had COVID-19 outbreaks (1741 residents, 1972 beds). Median time from first case of COVID-19 in Ireland to first case in these NHs was 27.0 days. Resident COVID-19 incidence was (43.9%, 764/1741): laboratory-confirmed (40.1%, 710/1741) with (27.2%, 193/710 asymptomatic), and clinically-suspected (3.1%, 54/1741). Resident case-fatality was (27.6%, 211/764) for combined laboratory-confirmed/clinically-suspected COVID-19. Similar proportions of residents in NH with an early outbreak (<28days) versus a later outbreak developed confirmed/suspected COVID-19. A lower proportion of residents in NHs with early outbreaks had recovered compared to those with late outbreaks (37.4% vs 61.7%; X2=56.9, p<0.001). Among 675 NH staff across twenty-four sites who had confirmed/suspected COVID-19 (23.6%, 159/675) were asymptomatic. There was a significant correlation between the proportion of staff with symptomatic COVID-19 and resident numbers with confirmed/suspected COVID-19 (Spearmans rho=0.81, p<0.001). Conclusion: This study demonstrates COVID-19 impact on NH residents and staff. High infection rates lead to challenges in care provision.