We observed similar baseline titers between women and men (p = 0.61) but different trends; women demonstrated a weekly Ginsenoside Rb1 increase of 3.4% (95% CI 2.6%C4.2%) compared with 5.2% (95% CI 3.8%C6.6%) in men (p = 0.035). Conclusions In this study, N-antibody seropositivity was 29% among healthcare workers, and a small, sustained rise in antibody titers occurred over 12 weeks. 2 (SARS-CoV-2), the virus responsible for coronavirus disease (COVID-19), is of scientific and strategic interest for public health systems worldwide. After SARS-CoV-2 infection, antibodies are produced against multiple viral epitopes, including the nucleocapsid (N) protein, which is highly immunogenic and abundantly expressed (1). A key concern is the potential for rapid waning of antibodies and seroreversion (loss of detectable antibodies), as seen with other novel betacoronaviruses (2), which might represent declining immunity and could compromise serosurveillance. Frontline healthcare workers are a vital population for serosurveillance because they are at greater risk than the general population. We describe findings from a serosurveillance study conducted in London, UK, by Public Health England (PHE). The Study We conducted prospective serosurveillance of healthcare professionals in secondary care settings across London beginning March 30, 2020. Healthcare workers were recruited by hospital research teams and provided written informed consent. Demographic, occupational, and clinical Ginsenoside Rb1 data were collected at baseline, including self-reported previous laboratory-confirmed COVID-19. Participants provided blood samples and completed symptom surveys at baseline and 2-weekly intervals until July 21, 2020, reporting any new illness or COVID-19 diagnosis. Blood samples were centrifuged and frozen locally; PHE then tested serum samples by using the Elecsys Anti-SARS-CoV-2 total antibody assay (Roche, https://www.roche.com), according to the manufacturers instructions. This test is an electrochemiluminescence immunoassay for antibodies targeting the N protein Ginsenoside Rb1 (IgG, IgM, or IgA) and produces a numeric cutoff index derived from comparison of the sample and calibrator signals (3). The surveillance protocol was approved by the PHE Research Ethics Governance Group (R&D REGG Ref: NR0192, March 31, 2020). We compared differences in seropositivity between groups by using 2 tests and multivariable logistic regression to provide adjusted odds ratios (aORs). We estimated biweekly seroconversion and seroreversion rates and binomial 95% CIs. We analyzed trends in individual-level antibody responses beginning 4 weeks after the first positive antibody test, which allowed time for responses to stabilize. We used mixed effects regression to analyze trends in log antibody titers and assessed fixed effects for differences Ginsenoside Rb1 in antibody response through likelihood ratio tests. Surveillance involved 1,069 participants from 4 hospitals: Charing Cross (n = 192), Northwick Park (n = 217), Royal Free (n = 126), and St. Georges (n = 534). Of these, 850 participants had >4 sampling visits and 395 >6 sampling visits (over 10C12 weeks of follow-up). Overall, 312 (29%) participants had >1 positive antibody test (95% CI 26%C32%); of Rabbit polyclonal to GSK3 alpha-beta.GSK3A a proline-directed protein kinase of the GSK family.Implicated in the control of several regulatory proteins including glycogen synthase, Myb, and c-Jun.GSK3 and GSK3 have similar functions. those, 181 (58%) had >8 weeks and 42 (13%) 12 weeks of follow-up after the first positive test (Appendix Table 1). Seropositivity varied between hospitals (p = 0.042), from 25% to 35%. In total, 109 (10.2%) participants self-reported laboratory-confirmed COVID-19, 407 (32%) reported respiratory illness, 5 (0.47%) reported hospitalization, and 794 (61%) did not report illness. We observed no difference in seropositivity by sex, profession, performance of aerosol-generating procedures, employment in the emergency department, or immunocompromised status (Appendix Table 2). Participants 25C34 years of age had higher odds of seropositivity than those 35C44 years of age (aOR?1.57, 95% CI 1.09C2.26), but little difference was seen among older age groups. Those working in intensive care units had lower odds of seropositivity than participants from other hospital departments (aOR?0.58, 95% CI 0.38C0.91). Most seropositive participants tested positive at baseline (279/312, 89%). Only 33 participants seroconverted during follow-up, corresponding to a biweekly rate of 1 1.2% (95% CI 0.8%C1.7%). We observed 4 seroreversions, corresponding to a biweekly rate of 0.4% (95% CI 0.1%C0.9%). log antibody titers remained stable over time in seropositive participants, and little within-individual variability was observed (Figure). The general trend across all subgroups was a slight increase over time, although data are sparse for some groups. Open in a separate window Figure log antibody titers over time in participants with >1 positive test result by subgroups in study of nucleocapsid-antibody response in.