Patient and ward related risk factors in a multi-ward nosocomial outbreak of COVID-19: Outbreak investigation and matched case–control study

Abstract

Background Risk factors for nosocomial COVID-19 outbreaks continue to evolve. The aim of this study was to investigate a multi-ward nosocomial outbreak of COVID-19 between 1st September and 15th November 2020, occurring in a setting without vaccination for any healthcare workers or patients. Methods Outbreak report and retrospective, matched case–control study using incidence density sampling in three cardiac wards in an 1100-bed tertiary teaching hospital in Calgary, Alberta, Canada. Patients were confirmed/probable COVID-19 cases and contemporaneous control patients without COVID-19. COVID-19 outbreak definitions were based on Public Health guidelines. Clinical and environmental specimens were tested by RT-PCR and as applicable quantitative viral cultures and whole genome sequencing were conducted. Controls were inpatients on the cardiac wards during the study period confirmed to be without COVID-19, matched to outbreak cases by time of symptom onset dates, age within ± 15 years and were admitted in hospital for at least 2 days. Demographics, Braden Score, baseline medications, laboratory measures, co-morbidities, and hospitalization characteristics were collected on cases and controls. Univariate and multivariate conditional logistical regression was used to identify independent risk factors for nosocomial COVID-19. Results The outbreak involved 42 healthcare workers and 39 patients. The strongest independent risk factor for nosocomial COVID-19 (IRR 3.21, 95% CI 1.47–7.02) was exposure in a multi-bedded room. Of 45 strains successfully sequenced, 44 (97.8%) were B.1.128 and differed from the most common circulating community lineages. SARS-CoV-2 positive cultures were detected in 56.7% (34/60) of clinical and environmental specimens. The multidisciplinary outbreak team observed eleven contributing events to transmission during the outbreak. Conclusions Transmission routes of SARS-CoV-2 in hospital outbreaks are complex; however multi-bedded rooms play a significant role in the transmission of SARS-CoV-2.

Barriers to healthcare-worker adherence to infection prevention and control practices in British Columbia during the coronavirus disease 2019 (COVID-19) pandemic: A cross-sectional study

“…For example, a higher proportion of private patient rooms was associated with a lower risk of healthcare-associated infections prior to the pandemic. 27 , 28 During the pandemic, more crowded long-term care facilities were found to have more than double the rate of COVID-19 mortality. 29 , 30 Addressing these operational challenges will require collaboration among multidisciplinary teams, including IPAC, across the healthcare system.…”

Non-pharmaceutical interventions for COVID-19: a systematic review on environmental control measures

“…Surface disinfection: Contamination of surfaces in houses or hospital wards housing individuals with COVID-19 suggests that fomite transmission may be possible [70][71][72]. Lin et al studied secondary transmission to HCWs that performed gastrointestinal endoscopy in 11 COVID-19 patients at a hospital in China, where enhanced disinfection strategies were in place both during and after the procedures.…”

The association between non-communicable diseases and COVID-19 severity and mortality among infected hospitalized healthcare workers in 29 countries: a cohort study

“…This novel virus continued to evolve and spread with emerging strains accounting for increased risk of transmission and different degrees of disease severity within the community and in healthcare settings. 6 Healthcare workers (HCWs) bore the brunt of the pandemic through occupational exposure as they cared for COVID-19 patients. 7 There is a growing body of evidence showing that HCWs were at higher risk of contracting the virus compared to the general population, as they cared for COVID-19 patients.…”