Comparing Dynamics and Determinants of SARS-CoV-2 Transmissions Among Health Care Workers of Adult and Paediatric Settings in Central Paris

Background: From the start of the pandemic, health-care workers (HCW) have paid a heavy toll to the coronavirus desease-19 (COVID-19) outbreak. Routes of transmission however remain to be fully understood. Methods: This prospective study compared two settings of a tertiary-care university hospital located in central Paris: a 1,500-bed adult and a 600-bed paediatric setting, accounting for a total of 13,278 employees. From February 24th until April 10th, 2020, all symptomatic HCW were screened for severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) on a nasopharyngeal swab. HCW screened positive were prospectively questioned by phone on their profession, symptoms, occupational and non-occupational exposures to SARS-CoV-2. Findings: Among 1344 symptomatic HCW tested, 373 were positive (28%) and 336 (90%) corresponding questionnaires were completed. Three hospitalizations and no death have been reported. Most HCW (70%) had patient-facing occupational activities and 22% in COVID-19 dedicated units. The total number of HCW cases peaked on week 13 (March 23rd, 2020) then decreased slowly until April 10th, concomitantly with a continuous increase of compliance to preventive measures (including universal medical masking for all hospital staff and personal protective equipment (PPE) for direct care to COVID-19 patients). Attack rates were of 3 · 2% and 2 · 3% in the adult and paediatric settings, respectively (p=0 · 0022). In the adult setting, HCW more frequently reported exposure to COVID-19 patients without PPE (25% versus 15%, p=0 · 046). In both settings, report of contacts with children attending out-of-home care facilities dramatically decreased all over the study period. Interpretation: In central Paris, implementation of universal masking, reinforcement of hand hygiene, social distancing and PPE with medical masks for patients’ care allowed protection of HCW and containment of the outbreak. Residual transmissions were related to persistent exposures with undiagnosed patients or colleagues and not to contacts with children attending out-of-home care facilities. Funding Statement: None. Declaration of Interests: AC reports personal fees and non-financial support from Janssen Cilag, outside the submitted work. RG reports personal fees and other from Sanofi, personal fees from MSD, personal fees from Eumedica, personal fees from Pfizer, personal fees from Frezenius, personal fees from Cubist, personal fees from Correvio, personal fees from Astellas, outside the submitted work. PF reports personal fees and nonfinancial support from MSD France, personal fees from ViiV Healthcare, non-financial support from Gilead Science, personal fees and non-financial support from Janssen Cilag, personal fees from Medtronic SAS, non-financial support from Astellas, non-financial support from GSK, outside the submitted work. MLV reports non-financial support from Biomerieux, non-financial support from Diasorin, outside the submitted work. OL reports personal fees from Pfizer, personal fees from Astellas, personal fees from MSD, personal fees from Gilead, outside the submitted work. SK reports research grants from bioMerieux, personal fees from Accelerate Diagnostics, bioMerieux, MSD and Menarini, and travel expenses from bioMerieux, Astellas, MSD and Pfizer, outside the submitted work. All other authors declare no conflict of interests. Ethics Approval Statement: This study was approved by the Ethical Review Committee for publications of the Cochin university Hospital (CLEP) (N°: AAA-2020-08012). According to French policy, a non-opposition statement was obtained for all participants, meaning that all had received written detailed information on the objectives of the study and were free to request withdrawal of their consent for participation at any time.