Investigation of A COVID-19 Cluster Infection in An Apartment Building, Northern Taiwan, 2021

Investigation of A COVID-19 Cluster Infection in An Apartment Building, Northern Taiwan, 2021

On July 29, 2021, Taiwan Centers for Disease Control (Taiwan CDC) received a notification that a patient living in an apartment was confirmed to be infected with COVID-19. From August 4–8, three more cases were confirmed from the same building. The Department of Health from New Taipei City government started epidemiological investigation immediately. Furthermore, expanded community screening was implemented. Simultaneously, Taiwan CDC executed environmental risk assessment and collected environmental samples for testing. As a whole, 283 contacts were subjected to home quarantine, including 8 cohabitant of the confirmed patients, 19 close contacts, 18 workplace contacts and 238 building resident contacts. After the expanded community screening, 2 more cases were confirmed on August 9, while the other 281 contacts showed negative results in the screening. Totally 6 patients were confirmed with COVID-19 infection, presumably the transmission was aerosol originated either by using same elevators, waiting in a same place, or by sharing a same air conduit since there were 3 families living under the vertically connected airpipes. Improving ventilation was recommended to reduce the risk of disease spreading.