Hospital contact patterns and vulnerability to SARS-CoV-2 outbreaks

The transmission risk of SARS-CoV-2 within hospitals can exceed that in the general community because of more frequent close proximity interactions (CPIs). Heterogeneity of risk across wards is still poorly described. We measured CPIs in 15 clinical wards across three hospitals using wearable sensors over 36 hours in spring 2020. This data was combined with a transmission model to estimate and compare transmission risks across wards. We found a four-fold range of epidemic risk between wards, with patients frequently presenting high risk to patients and healthcare workers (HCWs). Using a simulation study, we then assessed the potential impact on global risk of targeting individuals for prevention based on their contact patterns. We found that targeting individuals with the highest cumulative contact hours was most impactful. This study reveals patterns of interactions between individuals in hospital during a pandemic and opens new routes for research into airborne nosocomial risk. One Sentence SummaryWe measured contacts between staff, patients and visitors in 15 hospital wards, and used models to predict epidemic risk and evaluate interventions.

Comparing dynamics and determinants of SARS-CoV-2 transmissions among health care workers of adult and pediatric settings in central Paris

BackgroundFrom the start of the pandemic, health-care workers (HCW) have paid a heavy toll to the coronavirus disease-19 (COVID-19) outbreak. ObjectivesTo describe the dynamics and determinants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection in HCW. DesignProspective observational study conducted from February 24th until April 10th, 2020. SettingComparison of a 1,500-bed adult and a 600-bed pediatric setting of a tertiary-care university hospital located in central Paris. ParticipantsAll symptomatic HCW screened for SARS-CoV-2 on a nasopharyngeal swab. MeasurementsHCW screened positive were prospectively questioned on their profession, symptoms, occupational and non-occupational exposures to SARS-CoV-2. ResultsAmong 1344 symptomatic HCW tested, 373 were positive (28%) and 336 (90%) corresponding questionnaires were completed. Three hospitalizations and no death were reported. Most HCW (70%) had patient-facing occupational activities (22% in COVID-19 dedicated units). The total number of HCW cases peaked on March 23rd, then decreased slowly, concomitantly with a continuous increase of compliance to preventive measures (including universal medical masking 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 pediatric setting, 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). Report of contacts with children attending out-of-home care facilities dramatically decreased over the study period. LimitationsLack of COVID-19 negative controls and recall bias. ConclusionUniversal masking, reinforcement of hand hygiene, 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.