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) have been reported globally during the recent pandemic. Unfortunately, these clusters negatively affect inpatient morbidity, mortality, and hospital functioning. Using epidemiological data and whole-genome sequencing (WGS) of SARS-CoV-2, this study investigated the outbreak of COVID-19 at a university hospital. Eight inpatients and 13 healthcare workers tested positive for SARS-CoV-2 during a 1-month period. WGS of the virus in 11 patients revealed that the two variants of concern belonging to the Omicron sublineages, BA.2.3 and BA1.1.2, caused an outbreak when the proportion of the Omicron lineage in the community changed. When variants of concern undergo 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. Awareness of infection prevention and control should be raised to safeguard patient safety.