An outbreak of SARS-CoV-2 reinfection in a long-term care facility in South Korea.

We report a cluster of 12 cases of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection in a long-term care facility in South Korea. There were two outbreaks of SARS-CoV-2 infection in the facility at the beginning and end of October 2021, respectively. All residents in the facility were screened for SARS-CoV-2 infection using RT-PCR as part of the investigation of the second outbreak. Twelve residents, who had infection confirmed during the first outbreak, were found to be re-positive for RT-PCR test at the second outbreak. 8 Of 12 RT-PCR re-positive cases were confirmed as reinfections based on investigation through the whole genome sequencing, viral culture, and serological analysis, despite of the short interval between the first and second outbreaks (29-33 days) and a history of full vaccination for 7 of the 12 re-positive cases. This study suggests that decreased immunity and underlying health condition in older adults makes them susceptible to reinfection, highlighting the importance of prevention and control measures regardless of vaccination status in long-term care settings.