COVID-19 exposure in SARS-CoV-2-seropositive hospital staff members during the first pandemic wave at Strasbourg University Hospital, France.

OBJECTIVES: Strasbourg University Hospital faced an important COVID-19 first wave from early March 2020. We performed a longitudinal prospective cohort study to describe clinical and virological data, exposure history to COVID-19, and adherence to strict hygiene standards during the first pandemic wave in 1497 workers undergoing a SARS-CoV-2 serological test at our hospital, with a follow up of serology result three months later. PATIENTS AND METHODS: A total of 1497 patients were enrolled from April 6 to May 7, 2020. Antibody response to SARS-CoV-2 was measured, and COVID-19 exposure routes were analyzed according to SARS-CoV-2 serological status. RESULTS: A total of 515 patients (34.4%) were seropositive, mainly medical students (13.2%) and assistant nurses (12.0%). A history of COVID-19 exposure in a professional and/or private setting was mentioned by 83.1% of seropositive subjects (P<0.05; odds ratio [OR]: 2.5; 95% confidence interval [CI]: 1.8-3.4). COVID-19 exposure factors associated with seropositive status were non-professional exposure (OR: 1.9, 95% CI: 1.3-2.7), especially outside the immediate family circle (OR: 2.2, 95% CI: 1.2-3.9) and contact with a COVID-19 patient (OR: 1.6; 95% CI: 1.1-2.2). Among professionally exposed workers, systematic adherence to strict hygiene standards was well observed, except for the use of a surgical mask (P<0.05, OR: 1.9, 95% CI: 1.3-2.8). Of those who reported occasionally or never wearing a surgical mask, nurses (25.7%), assistant nurses (16.2%), and medical students (11.7%) were predominant. CONCLUSION: Infection of staff members during the first pandemic wave in our hospital occurred after both professional and private COVID-19 exposure, underlining the importance of continuous training in strict hygiene standards.

Evolution of antibody responses up to 13 months after SARS-CoV-2 infection and risk of reinfection.

BACKGROUND: Assessment of the kinetics of SARS-CoV-2 antibodies is essential in predicting risk of reinfection and durability of vaccine protection. METHODS: This is a prospective, monocentric, longitudinal, cohort clinical study. Healthcare workers (HCW) from Strasbourg University Hospital were enrolled between April 6th and May 7th, 2020 and followed up to 422 days. Serial serum samples were tested for antibodies against the Receptor Binding Domain (RBD) of the spike protein and nucleocapsid protein (N) to characterize the kinetics of SARS-CoV-2 antibodies and the incidence of reinfection. Live-neutralization assays were performed for a subset of samples before and after vaccination to analyze sensitivity to SARS-CoV-2 variants. FINDINGS: A total of 4290 samples from 393 convalescent COVID-19 and 916 COVID-19 negative individuals were analyzed. In convalescent individuals, SARS-CoV-2 antibodies followed a triphasic kinetic model with half-lives at month (M) 11-13 of 283 days (95% CI 231-349) for anti-N and 725 days (95% CI 623-921) for anti-RBD IgG, which stabilized at a median of 1.54 log BAU/mL (95% CI 1.42-1.67). The incidence of SARS-CoV-2 infections was 12.22 and 0.40 per 100 person-years in COVID-19-negative and COVID-19-positive HCW, respectively, indicating a relative reduction in the incidence of SARS-CoV-2 reinfection of 96.7%. Live-virus neutralization assay revealed that after one year, variants D614G and B.1.1.7, but less so B.1.351, were sensitive to anti-RBD antibodies at 1.4 log BAU/mL, while IgG ≥ 2.0 log BAU/mL strongly neutralized all three variants. These latter anti-RBD IgG titers were reached by all vaccinated HCW regardless of pre-vaccination IgG levels and type of vaccine. INTERPRETATION: Our study demonstrates a long-term persistence of anti-RBD antibodies that may reduce risk of reinfection. By significantly increasing cross-neutralizing antibody titers, a single-dose vaccination strengthens protection against variants. FUN1DING: None.

[Myocardial injury in coronavirus disease 19 (Covid-19): main pathophysiological mechanisms and clinical utility of cardiac biomarkers]. / Atteintes myocardiques au cours de la maladie à coronavirus 19 (Covid-19) : principaux mécanismes physiopathologiques et utilité clinique des biomarqueurs cardiaques.

Covid-19 is responsible for myocardial injury in many infected patients, which is associated with severe disease and critical illness. The mechanisms by which SARS-CoV-2 may cause myocardial damage involve direct effect of the virus in cardiac cells and indirect effect due to the clinical consequences of Covid-19. Cardiomyocytes are well known to express Angiotensin-Converting Enzyme-2 receptors (ACE-2) to facilitate the virus cell entry, which could explain the occurrence of myocarditis, functional alterations in the myocardium, and more rarely, myocardial infarction. Myocardial injury may also be secondary to systemic inflammation or coagulopathy due to complicated Covid-19. The existence of a cardio-intestinal axis with alteration of tryptophan metabolism in the small bowel leading first to colitis and then to systemic inflammation has also been evoked to explain the myocardial injury. Morphological and metabolic disturbances of the heart during the Covid-19 are associated with elevated concentrations of cardiac blood biomarkers, mainly troponins and natriuretic peptides. The determination of these biomarkers has proven to be very useful for diagnosis, prognosis, and risk stratification. Indeed, recent data demonstrated that about 20% of infected patients admitted to the hospital have elevated troponin or BNP levels, and Covid-19 patients with elevated troponin concentrations beyond the diagnostic threshold (99th percentile) were associated with a higher risk of in-hospital mortality. In conclusion, after more than a year of a unique global pandemic, it is now clearly established that myocardial injury during Covid-19 is frequent and strongly contributes to the severity of the disease. Cardiac alterations secondary to direct infection of cardiac cells by SARS-CoV-2 or to the clinical consequences of Covid-19 are associated with elevated levels of cardiac biomarkers in blood, whose measurement is crucial in clinical decision making.