Association between SARS-CoV-2 Seroprevalence in Nursing Home Staff and Resident COVID-19 Cases and Mortality: A Cross-Sectional Study.

Ania Wisniak,Idris Guessous,The Serocov-Work + Study Group ,Silvia Stringhini,Omar Kherad,María-Eugenia Zaballa,Didier Pittet,Jean-François Balavoine,Richard Dubos,Hélène Baysson,Roxane Dumont,Simon Regard,Nick Pullen,Lakshmi Krishna Menon,Laurent Kaiser,Delphine Courvoisier,Andrew S Azman

doi:10.3390/v14010043

Abstract

The burden of COVID-19 has disproportionately impacted the elderly, who are at increased risk of severe disease, hospitalization, and death. This cross-sectional study aimed to assess the association between SARS-CoV-2 seroprevalence among nursing home staff, and cumulative incidence rates of COVID-19 cases, hospitalizations, and deaths among residents. Staff seroprevalence was estimated within the SEROCoV-WORK+ study between May and September 2020 across 29 nursing homes in Geneva, Switzerland. Data on nursing home residents were obtained from the canton of Geneva for the period between March and August 2020. Associations were assessed using Spearman’s correlation coefficient and quasi-Poisson regression models. Overall, seroprevalence among staff ranged between 0 and 31.4%, with a median of 8.3%. A positive association was found between staff seroprevalence and resident cumulative incidence of COVID-19 cases (correlation coefficient R = 0.72, 95%CI 0.45–0.87; incidence rate ratio [IRR] = 1.10, 95%CI 1.07–1.17), hospitalizations (R = 0.59, 95%CI 0.25–0.80; IRR = 1.09, 95%CI 1.05–1.13), and deaths (R = 0.71, 95%CI 0.44–0.86; IRR = 1.12, 95%CI 1.07–1.18). Our results suggest that SARS-CoV-2 transmission between staff and residents may contribute to the spread of the virus within nursing homes. Awareness among nursing home professionals of their likely role in the spread of SARS-CoV-2 has the potential to increase vaccination coverage and prevent unnecessary deaths due to COVID-19.

Highlights

Since the beginning of the pandemic, the burden of COVID-19 has been greater among the elderly and people with comorbidities, who are at increased risk of severe disease, hospitalization, and death [1]
Seroprevalence among staff ranged between 0 and 31.4% in individual nursing homes, with a median of 12.5% (IQR 4.4–20.5%). This contrasted with COVID-19 cases among staff reported by nursing homes, which ranged between 0 and 1.4% of total workers by nursing home, with only five (0.16%) COVID-19 cases detected among the staff of all included nursing homes for the study period
We observed a large gap between the reported number of COVID-19 cases in nursing home staff and the seroprevalence rates identified in our study which were approximately 90-fold higher (0.16% vs. 14.4%)

Summary

Introduction

Since the beginning of the pandemic, the burden of COVID-19 has been greater among the elderly and people with comorbidities, who are at increased risk of severe disease, hospitalization, and death [1]. In Switzerland, 49% of all COVID-19-related deaths occurred in nursing homes, not taking into account residents who died in hospitals [3]. A large proportion of asymptomatic or undetected COVID-19 cases among nursing home staff has been described in several studies worldwide and may contribute to silent SARSCoV-2 transmission within nursing homes [8,9]. The higher vulnerability of this population to severe disease due to their advanced age is another important factor that should be considered. To what extent these different elements contribute to the high COVID-19 mortality within nursing homes remains unclear

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