COVID-19 Prevalence in UNIVI Group Nursing Homes and Multilevel Geriatric Hospitals: Epidemiological Study of Immunological Status with Rapid Serological Tests for Diagnostic Guidance and Follow Up

BACKGROUND/OBJECTIVES: To date, data are lacking on the proportion of residents, and employees who have actually been exposed to SARS-Cov-2 in nursing homes and geriatric healthcare institutions, as well as the evolution of their serological status and the recurrence of Covid-19. The primary objective was to determine the prevalence of COVID-19 using NG Biotech rapid serological tests among caregivers and residents. The secondary objectives were to determine: prevalence according to RT PCR tests or clinical diagnosis; the risk factors (autonomy, arterial hypertension, diabetes mellitus) and clinical presentation (e.g. respiratory, abdominal or cutaneous symptoms, asthenia, fever) among residents; the risk factors (age, sex, profession, family situation) among caregivers; the evolution of the serological status at 1, 3 and 6 months using NG Biotech rapid serological tests; the symptomatic recurrence of Covid 19 at 1, 3 and 6 months. DESIGN: Multicentric prospective observational. SETTING: Study location: 27 nursing homes and 3 multilevel geriatric hospitals belonging to the UNIVI Group in France. PARTICIPANTS: 1334 professionals: 692 among multilevel geriatric hospitals (mean age: 43.6+/−11.8; 441 (82.4%) female) and 642 among nursing homes (mean age: 43.5+/−12.4; 685 (85.9%) female), and 1145 residents (mean age: 89+/−7.5; 898 (78.7%) female). MEASUREMENTS: Prevalence using NG Biotech rapid serological tests, medical diagnosis, RT-PCR tests. Risk factors among residents using the medical file and among caregivers using questionnaires. Clinical presentation in residents using the medical file. RESULTS: The prevalence using NG Biotech rapid serological test in residents was 14.4 % (168 of 1142 available diagnostics), the global prevalence (positive RT-PCR or positive serological test) was 22.7% (203 of 895 available diagnostics). The prevalence using NG Biotech rapid serological test in professionals was 12.8% (164 of 1315 available diagnostics), the global prevalence (positive RT-PCR test or positive serological test) was 23.8% (222 of 933 available diagnostics). The risk factors among residents were: living in an Alzheimer unit, and being a contact case. Being independent for activities of daily living was protective. The risk factor among caregivers was being a contact case. Another risk factor was the job; nurse assistants, nurses, and physicians were the most exposed. Residents had atypical clinical presentations including frequent geriatric syndromes (falls, delirium). 68.3% (71 of 104) of the initially positive residents still had a positive rapid serological test at 1 month follow up and 74 % (54 of 73) at 3 months follow up. 77.9% (88 of 113) of the initially positive employees still had a positive rapid serological test at 1 month follow up. Symptomatic reinfection was exceptional in caregivers or in residents during follow up. CONCLUSION: COVID 19 prevalence among caregivers and residents in nursing homes and geriatric health Institutions is underestimated when using only one method for diagnosis. Geriatric syndromes such as falls and delirium in residents should trigger further investigations on a COVID-19 cause. Immunity was persistent in ¾ of caregivers and residents during the 3 months follow up. The high prevalence of COVID 19 in geriatric institutions pleads in favor of the French vaccination policy, initially targeting as a priority the most vulnerable and dependent people, followed by staff members in healthcare institutions and nursing homes. More studies on the persistence of immunity and the perspective of Covid 19 mutations will help determine the long-term vaccine booster policy.