COVID-19 outbreak in acute care hospital linked to vaccine breakthrough

Editor's Note

This study by researchers in South Korea analyzes a COVID-19 outbreak caused by vaccine breakthrough infections in a hospital where 91.9% of healthcare workers were vaccinated. In addition, it was mandatory that all healthcare workers and caregivers wear masks or respirators at all times except when eating.

During the outbreak, 94 individuals tested positive for COVID-19, including 61 healthcare workers, 18 patients, and 15 caregivers. Nearly 75% were vaccine breakthrough infections.

More than 86% of transmissions appeared to be caused by three index cases, and 58% of cases were associated with the hospital staff cafeteria and offices located in the basement of the main building. There were no windows on the basement floor, and ventilation was provided with multiblade fans; this building also had two central air-conditioning systems.

The most important cause of the outbreak was the delay in diagnosis (6 days) in the index healthcare workers after onset of symptoms, the researchers note. Of the infected healthcare workers and caregivers, only one required oxygen supplementation; whereas, four patients died, three of which were unvaccinated.

Efforts to minimize transmission should include meticulous screening of COVID-19 symptoms in healthcare workers and care givers as well as adequate ventilation, the researchers concluded. Following this outbreak, an air handling unit was installed in the basement cafeteria.