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

Abstract

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.

Antibody response in elderly vaccinated four times with an mRNA anti-COVID-19 vaccine

“…The data presented, based on paired blood samples collected after the third and the fourth doses of the same mRNA vaccine, describe the humoral response of a well-protected elderly population (85 years, median) of whom 87% (n = 40) were never infected by SARS-CoV-2. Subsequently, as the residents were tested on a weekly basis and 40 were found free of SARS-CoV-2 during April 2020–May 2022, this study allowed the comparative evaluation of levels of anti-RBD IgG and nAb induced by the third and fourth dose of vaccine without the noise of potential COVID-19, including asymptomatic cases as described by Friedman et al 19 .…”

“…We could not sample the elderly residents exactly a week before and three weeks after each booster to optimally evaluate their humoral response for ethical reasons: venous blood samples among elderly participants should be limited. Although the residents were tested weekly for the presence of SARS-CoV-2 during the whole period of the study, some asymptomatic cases may have been undiagnosed, which could result in some outliers 19 , 21 . However, anti-nucleocapsid IgG were not found at a significant level among the residents except for one breakthrough infection individual.…”

Neutralizing Antibody Responses Among Residents and Staff of Long-Term Care Facilities in the State of New Jersey During the First Wave of the COVID-19 Pandemic

“…Residents and staff of 10 LTCFs in the state of New Jersey had provided informed consent and phlebotomy from November 2020 through March 2021 [ 22 ]. Subjects with remaining serum from the original study were tested for neutralizing antibodies against SARS-CoV-2 by the semi-quantitative cPass neutralization-antibody detection assay (GenScript, Piscataway, NJ).…”

“…As an ELISA, the test allows rapid testing of large numbers of specimens. The Rutgers New Jersey Medical School and the New Jersey State Department of Health previously reported the incidence of SARS-CoV-2 infection and the prevalence of IgG antibody to the nucleocapsid protein among residents and staff of 10 LTCFs in New Jersey in the first wave of the pandemic [ 22 ]. In this study we used this new neutralizing antibody test to further characterize this antibody response among residents and staff.…”