SARS-CoV-2 Seroprevalence and Antibody Kinetics Among Health Care Workers in a Spanish Hospital After 3 Months of Follow-up.

BACKGROUND: At the COVID-19 spring 2020 pandemic peak in Spain, prevalence of SARS-CoV-2 infection in a cohort of 578 randomly selected health care workers (HCWs) from Hospital Clínic de Barcelona was 11.2%. METHODS: A follow-up survey 1 month later (April-May 2020) measured infection by rRT-PCR and IgM, IgA, and IgG to the receptor-binding domain of the spike protein by Luminex. Antibody kinetics, including IgG subclasses, was assessed until month 3. RESULTS: At month 1, the prevalence of infection measured by rRT-PCR and serology was 14.9% (84/565) and seroprevalence 14.5% (82/565). We found 25 (5%) new infections in 501 participants without previous evidence of infection. IgM, IgG, and IgA levels declined in 3 months (antibody decay rates 0.15 [95% CI, .11-.19], 0.66 [95% CI, .54-.82], and 0.12 [95% CI, .09-.16], respectively), and 68.33% of HCWs had seroreverted for IgM, 3.08% for IgG, and 24.29% for IgA. The most frequent subclass responses were IgG1 (highest levels) and IgG2, followed by IgG3, and only IgA1 but no IgA2 was detected. CONCLUSIONS: Continuous and improved surveillance of SARS-CoV-2 infections in HCWs remains critical, particularly in high-risk groups. The observed fast decay of IgA and IgM levels has implications for seroprevalence studies using these isotypes.

Effectiveness of tixagevimab/cilgavimab in reducing SARS-CoV-2 infections, hospitalizations and mortality in inmunocompromised patients. / Efectividad de tixagevimab/cilgavimab en la reducción de la infección, ingresos hospitalarios y mortalidad por SARS-CoV-2 en pacientes inmunodeprimidos.

INTRODUCTION: Inmunocompromised people have higher SARS-CoV-2 morbi-mortality and they are subsidiary to receive pre-exposure prophylaxis. The objective of this study is to evaluate the effectiveness of tixagevimab/cilgavimab (Evusheld) in preventing SARS-CoV-2 infections, hospitalizations and mortality in immunocompromised patients. MATERIALS AND METHODS: 119 immunocompromised people>18 years old eligible of receiving Evusheld were followed for 6 months. People with previous SARS-CoV-2 infection or incomplete vaccination regimen were exluded. A total of 19 people who received Evusheld were matched by propensity score, using a 1:1 ratio, with another 19 people who did not receive Evusheld. Sociodemographic, related to SARS-CoV-2 risk factors and related to immunosuppression variables were included. The dependent variables were infection, hospitalization, and mortality related to SARS-CoV-2. Statistical analyzes were performed using SPSS Statistics 19.0, STATA 11.0, and the R statistical package. RESULTS: In total, 4 people in the Evusheld group and 11 in the control group had SARS-CoV-2 infection, showing an incidence rate of 3.87 and 13.62 per 100 person-months, respectively. The HR (Hazard Ratio) was 0.29 (95% CI=0.09-0.90) for SARS-CoV-2 infection, 0.37 (0.07-1.92) for SARS-CoV-2 hospitalization and, 0.23 (0.03-2.09) for SARS-CoV-2 mortality in the Evusheld group compared to control group. CONCLUSIONS: This study demonstrates that Evusheld reduces the SARS-CoV-2 infections.

Seven-month kinetics of SARS-CoV-2 antibodies and role of pre-existing antibodies to human coronaviruses.

Unraveling the long-term kinetics of antibodies to SARS-CoV-2 and the individual characteristics influencing it, including the impact of pre-existing antibodies to human coronaviruses causing common cold (HCoVs), is essential to understand protective immunity to COVID-19 and devise effective surveillance strategies. IgM, IgA and IgG levels against six SARS-CoV-2 antigens and the nucleocapsid antigen of the four HCoV (229E, NL63, OC43 and HKU1) were quantified by Luminex, and antibody neutralization capacity was assessed by flow cytometry, in a cohort of health care workers followed up to 7 months (N = 578). Seroprevalence increases over time from 13.5% (month 0) and 15.6% (month 1) to 16.4% (month 6). Levels of antibodies, including those with neutralizing capacity, are stable over time, except IgG to nucleocapsid antigen and IgM levels that wane. After the peak response, anti-spike antibody levels increase from ~150 days post-symptom onset in all individuals (73% for IgG), in the absence of any evidence of re-exposure. IgG and IgA to HCoV are significantly higher in asymptomatic than symptomatic seropositive individuals. Thus, pre-existing cross-reactive HCoVs antibodies could have a protective effect against SARS-CoV-2 infection and COVID-19 disease.

Seroprevalence of antibodies against SARS-CoV-2 among health care workers in a large Spanish reference hospital.

Health care workers (HCW) are a high-risk population to acquire SARS-CoV-2 infection from patients or other fellow HCW. This study aims at estimating the seroprevalence against SARS-CoV-2 in a random sample of HCW from a large hospital in Spain. Of the 578 participants recruited from 28 March to 9 April 2020, 54 (9.3%, 95% CI: 7.1-12.0) were seropositive for IgM and/or IgG and/or IgA against SARS-CoV-2. The cumulative prevalence of SARS-CoV-2 infection (presence of antibodies or past or current positive rRT-PCR) was 11.2% (65/578, 95% CI: 8.8-14.1). Among those with evidence of past or current infection, 40.0% (26/65) had not been previously diagnosed with COVID-19. Here we report a relatively low seroprevalence of antibodies among HCW at the peak of the COVID-19 epidemic in Spain. A large proportion of HCW with past or present infection had not been previously diagnosed with COVID-19, which calls for active periodic rRT-PCR testing in hospital settings.