Antibody Seroprevalence, Infection and Surveillance for SARS-CoV-2 in Residents and Staff of New Jersey Long-Term Care Facilities

Early in the pandemic, New Jersey (NJ) long-term care facilities (LTCFs) witnessed severe COVID-19 illness. With limited surveillance to characterize the scope of infection, we estimated the prevalence of antibody to the SARS-CoV-2 nucleocapsid protein among residents and staff, to describe the epidemiology, and to measure antibody distribution by prior PCR/antigen status and symptomatology. 10 NJ LTCFs of 20 solicited with diverse geography and bed-capacities were visited between October 2020 and March 2021. A single serum was tested for total N-antibody (ELISA) by the state laboratory. Residents’ demographics and clinical history were transcribed from the patient record. For staff, this information was solicited directly from employees, supplemented by prior PCR/antigen results from facilities. 62% of 332 residents and 46% of 661 staff tested N-antibody positive. In a multivariable logistic regression in residents, odds ratios for older age and admission prior before March 1, 2020 were significant. Among the staff, odds ratios for older age, ethnic-racial group, nursing-related job, and COVID-19 symptoms were significantly associated with N-antibody positivity. In a sub-analysis in five better record-keeping LTCFs, 90% of residents and 85% of staff with positive PCR/antigen results were seropositive for N-antibody, yet 25% of residents and 22% of staff were N-antibody positive but PCR/antigen and symptoms negative. The high rate of clinically unsuspected infections likely contributed to the spread. These findings argue for robust surveillance, regular screening of asymptomatic individuals, and vaccinating both residents and staff to abate the pandemic. The data also provide guidance to prevent future outbreaks.