COVID-19: How an office outbreak in South Korea shows that protecting workers is vital for relaxing lockdown

Office workers may be facing a heightened risk of COVID-19 infection, according to a South Korean study. The investigation by the Korea Centers for Disease Control and Prevention (KCDC) into an outbreak in a high-rise building in one of Seoul’s busiest districts has shown how the virus can trigger clustered infections.

It could have implications for decisions on how best to relax lockdown restrictions around the world. But it also illustrates the importance of taking prompt, effective action to limit the spread of infection.

Speed and scale of response

On 8 March, a COVID-19 outbreak was detected in a multi-use building in the South Korean capital, referred to as Building X. It has offices on its lower floors and residential apartments from floor 13 to 19. Once that first case had been found, a total of 1,145 people were placed under immediate investigation – 922 worked at the building, 203 lived there, plus 20 visitors. All but two were subsequently tested, with 97 confirmed cases of infection detected. That represents an attack or infection rate of 8.5% overall.

This kind of fast, decisive action has been the mainstay of South Korea’s response to the coronavirus pandemic. It’s helped the country avoid some of the problems others have faced – overwhelmed health services and high rates of death, to name but two. The strategy was outlined by South Korean Foreign Minister Kang Kyung-wha at a virtual World Economic Forum COVID Task Force meeting in March: an immediate response involving multiple agencies, and lots of communication with the public.

On 9 March, Building X was closed, demonstrating the rapid-action strategy favoured by the Korean authorities. People whose test results confirmed they had the coronavirus were isolated. Anyone they had come into contact with was also investigated, tested and monitored for 14 days, whether or not they displayed any symptoms.

Those who tested negative were ordered to stay quarantined for 14 days and were retested during their quarantine.

Using mobile phone data from telecoms operators, the authorities were able to identify people who had been in the near vicinity of the building. Anyone who had spent more than five minutes close to the building was sent a text message telling them to stay away from others and get themselves immediately tested. In total, 16,628 such text messages were sent out.

Office workers – the next vulnerable group?

Of the 97 people found to have the virus, most (94) worked at a call centre on the 11th floor of the building. When looking at the effect of the virus on the 216 people who worked on that floor, the attack rate jumps to 43.5%.

“This outbreak shows alarmingly that severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) can be exceptionally contagious in crowded office settings such as a call centre,” the report says.

Even though workers and residents at Building X came into close contact via shared facilities such as the elevators, the infection clustered around one set of people – those who worked near each other. This “indicates that the duration of interaction (or contact) was likely the main facilitator for further spreading of SARS-CoV-2,” the report continued.

As many countries around the world start to move toward relaxing their lockdown restrictions, there are concerns about how to get people back to work while keeping them safe and avoiding subsequent waves of severe infection. The Seoul study raises concerns about the virus’s capacity to create significant pockets of infection among office workers and demonstrates the importance of getting such decisions right.

“Targeted preventive strategies might help mitigate the risk for SARS-CoV-2 infection in (this) vulnerable group,” the report concludes.