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.

Expanding a previous study of the immune response to SARS-CoV-2 in 10 New Jersey long-term care facilities (LTCFs) during the first wave of the pandemic, this study characterized the neutralizing antibody (NAb) response to infection and vaccination among residents and staff. Sera from the original study were tested using the semi-quantitative enzyme-linked immunosorbent cPass neutralization-antibody detection assay. Almost all residents (97.8%) and staff (98.1%) who were positive for IgG S antibody to the spike protein were positive for NAb. In non-vaccinated subjects with a history of infection (positive polymerase chain reaction (PCR) or antigen test), the distribution of mean intervals from infection to serology date was not significantly different for S antibody positives versus negatives. More than 80% of both were positive at 10 months. Similarly, the mean NAb titer for residents and staff was not associated with interval from PCR/antigen positive to serology date, F = 0.1.01, Pr > F = 0.4269 and F = 0.77, Pr > F = 0.6548 respectively. Titers remained high as the interval reached 10 months. In vaccinees who had no history of infection, the NAb titer was near the test maximum when the serum was drawn seven or more days after the second vaccine dose. In staff the mean NAb titer increased significantly as the vaccine number increased from one to two doses, F = 11.69, Pr > F < 0.0001. NAb titers to SARS-CoV-2 in residents and staff of LTCFs were consistently high 10 months after infection and after two doses of vaccine. Ongoing study is needed to determine whether this antibody provides protection as the virus continues to mutate.

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.

Validation of the Diabetomics CovAB SARS-CoV-2 antibody test in children: comparison with serology.

Monitoring antibody prevalence is a valuable tool to evaluate the burden of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a community, identify risk factors, and assess the impact of clinical and public health intervention strategies. The antibody prevalence of SARS-CoV-2 in children in the United States in early 2022 was estimated by the Centers for Disease Control and Prevention to be 74.2%, using seroprevalence from a variety of sources. A study by the New Jersey Department of Health in late 2022/early 2023 in unvaccinated children found a lower prevalence, 68% when using a gum swab method to detect antibodies. This study compared the accuracy of the gum swab method to detect antibodies with simultaneously obtained serological samples in additional children. This cross-sectional study recruited well children, not vaccinated for SARS-CoV-2, aged 18 months to 11 years, who were scheduled for routine bloodwork at an inner-city university-based pediatric clinic. With parental consent, an extra 5 cc of blood and a gum swab sample were collected. Results from Diabetomics CovAb SARS-CoV-2 gum swab antibody test and Rutgers New Jersey Medical School enzyme-linked immunosorbent assay serology test for spike protein antibody were compared. The seropositivity of these paired samples was compared using McNemar's test, Cohen's kappa statistic, and other diagnostic accuracy statistics. From June through August 2023, 86 children were recruited. Antibody positivity by gum swab was 70.9% and by serology was 87.2%. The Cohen's kappa statistic was 0.39 indicating minimal agreement and McNemar's test was significant (P-value of 0.0010). Compared with serology, gum swab was 78.7% sensitive (95% CI 68.7% to 87.3%) and 81.8% specific (95% CI 48.2% to 97.7%). Positive and negative predictive values were 97.5% and 29.9%, respectively, and accuracy was 79.0%. Sensitivity in non-Hispanic versus Hispanic children was 74.2% versus 82.5%, and in children 6-11 years versus 18 months to 5 years, it was 74.2% versus 81.8%. While the gum swab method of antibody detection is not as sensitive or specific as serology, sample collection can be done in settings where phlebotomy is not feasible. This method could be useful in non-clinical settings such as surveillance, for assessing epidemiological trends and associations. IMPORTANCE: Recently a study determining the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies in unvaccinated children in NJ (Katic et al. 2023. Pediatric Academic Societies Meeting; Washington, D.C. https://2023.pas-meeting.org/searchbyposterbucket.asp?bm=Public+Health+%26+Prevention&t=Public+Health+%26+Prevention&pfp=Track) was conducted using a gum swab method for antibody detection. The Diabetomics CovAB test, which qualitatively identifies antibodies to SARS-CoV-2 spike protein, is a point-of-care, low-cost test, that is easy to administer in children. While this test provides sensitive and specific results in adults [US Food and Drug Administration (FDA). 2022. Center for devices and radiological health. EUA authorized serology test performance. Available from: https://www.fda.gov/medical-devices/covid-19-emergency-use-authorizations-medical-devices/eua-authorized-serology-test-performance], data on its accuracy in children is lacking. As a follow-up to the above-mentioned study, we compared the results of the gum swab test to a serologic antibody test. We found that the gum swab test was inferior to serology but was fairly sensitive and specific with a high positive predictive value. While the test is not ideal for diagnostic purposes in children it can be a valuable tool for public health officials and pediatricians to understand the extent of past health interventions.