Nosocomial outbreak of SARS-CoV-2 in a hospital ward during the Omicron variant-dominant wave with a review of the relevant literature

Clusters of nosocomial coronavirus disease 2019 (COVID-19) were reported globally during the recent pandemic. Unfortunately, these clusters negatively impacted inpatient morbidity, mortality, and hospital functions. Using epidemiological data and whole genome sequencing (WGS) of SARS-CoV-2, the present study investigated an outbreak of COVID-19 at a university hospital. Eight inpatients and 13 healthcare workers tested positive for SARS-CoV-2 during a one-month period. Whole genome sequencing (WGS) of the virus in 11 patients revealed that two variants of concern belonging to the Omicron sublineages, BA.2.3 and BA1.1.2, had caused the outbreak during a time when the proportion of the Omicron lineage in the community was changing. When variants of concern are undergoing mutation, a response to the outbreak should be made with multiple variants in mind, even in the absence of epidemiological data showing close contact or other potential vectors of infection, and awareness about infection prevention and control should be raised to safeguard patient safety.