ABSTRACT
Background. To describe post-COVID-19 vaccination [fully vaccinated (FV) and first booster] immune response and occurrence of reinfection ( >90 days from prior infection) in nursing home residents (NHr) with/without evidence of prior SARS-CoV-2 infection. Methods. In a longitudinal prospective cohort of 36 NHr from 3 NHs, interviews, chart ions, and specimens [blood and anterior nasal swabs (ANs)] were collected at baseline and monthly visits. ANs underwent molecular and BinaxNOWTM antigen testing. Quantitative Meso Scale Discovery platform tested blood specimens for anti-spike (S) protein and anti-nucleocapsid (N) antibodies. In addition, in a subset (n=13), S-specific memory B cells (MBCs) were tested with ELISpot assays. Results. The cohort's median age was 72 years;46% male, 64% White Non-Hispanic, 80% had >=3 comorbidities, and 29 (81%) had prior SARS-CoV-2 infection. Of 36, 76% received Pfizer-BioNTech and 24% Moderna homologous vaccine. The median distribution of anti-S IgG concentrations among those with prior infection increased 15-30 days post-FV, remained stable for 90 days, and declined by 120 days. The anti-S IgG remained above the estimated vaccine effectiveness (VE) thresholds published [Pfizer-BioNTech (95% VE: 530 BAU/ml), Moderna (90% VE: 298 BAU/ml)]. Among those without previous infection, anti-S IgG declined after 60 days and stayed near the VE thresholds until a recent infection/booster. Age, sex, and comorbidities had no appreciable impact on anti-S IgG. From enrollment to November 2021, 1of 29 had reinfection. From December 2021 to January 2022, 2 of 7 had a new infection, and 4 of 29 had reinfection, as shown by anti-N IgG rise. Persistently low numbers of total and anti-S MBC were seen across the evaluation, even with post-booster anti-S MBC rise. There was an immediate rise in anti-S IgG concentrations in all participants post-booster, irrespective of recent infection. Conclusion. These findings from a NH convenience cohort suggest that prior SARS-CoV-2 infection has a pronounced immunomodulatory enhancing effect on the magnitude and duration of FV immune response. The decline of anti-S antibodies post-FV and rise after booster supported the booster recommendation in this cohort. The low MBC counts indicate immunosenescence in this high-risk population.
ABSTRACT
Study objective: We determine the percentage of diagnosed and undiagnosed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among a sample of US emergency department (ED) health care personnel before July 2020. Methods: This was a cross-sectional analysis of ED health care personnel in 20 geographically diverse university-affiliated EDs from May 13, to July 8, 2020, including case counts of prior laboratory-confirmed coronavirus disease 2019 (COVID-19) diagnoses among all ED health care personnel, and then point-in -time serology (with confirmatory testing) and reverse transcriptase-polymerase chain reaction testing in a sample of volunteers without a previous COVID-19 diagnosis. Health care staff were categorized as clinical (physicians, advanced practice providers, and nurses) and nonclinical (clerks, social workers, and case managers). Previously undiagnosed infection was based on positive SARS-CoV-2 serology or reverse transcriptase-polymerase chain reaction result among health care personnel without prior diagnosis. Results: Diagnosed COVID-19 occurred in 2.8% of health care personnel (193/6,788), and the prevalence was similar for nonclinical and clinical staff (3.8% versus 2.7%;odds ratio 1.5;95% confidence interval 0.7 to 3.2). Among 1,606 health care personnel without previously diagnosed COVID-19, 29 (1.8%) had evidence of current or past SARS-CoV-2 infection. Most (62%;18/29) who were seropositive did not think they had been infected, 76% (19/25) recalled COVID-19-compatible symptoms, and 89% (17/19) continued to work while symptomatic. Accounting for both diagnosed and undiagnosed infections, 4.6% (95% confidence interval 2.8% to 7.5%) of ED health care personnel were estimated to have been infected with SARS-CoV-2, with 38% of those infections undiagnosed. Conclusion: In late spring and early summer 2020, the estimated prevalence of severe acute respiratory syndrome coronavirus 2 infection was 4.6%, and greater than one third of infections were undiagnosed. Undiagnosed SARS-CoV-2 infection may pose substantial risk for transmission to other staff and patients.