The individual, who worked as a salesman promoting health products to the elderly, had traveled from his home province of Heilongjiang to neighboring Jilin province, bringing the virus with him.
Authorities claim he unknowingly spread the virus among elderly residents for several days before he was tracked down by health officials as a close contact of a confirmed case.
“The superspreading phenomenon occurred in our province mainly because when the superspreader was discovered, he was still in the early phase of his infection and had relatively strong ability to shed the virus,” Zhao Qinglong, an official with the Jilin provincial disease control and prevention center, told state-run news agency Xinhua.
The apparent superspreading event in Jilin occurred as China is battling its worst coronavirus outbreak in months, which has seen hundreds of cases reported and tens of millions of people placed under lockdown in its northern provinces.
It also demonstrated the extent and speed of contact tracing and screening by Chinese health authorities, which have played a crucial role in taming local outbreaks.
Detailed itinerary and privacy concerns
The salesman was diagnosed as a confirmed case of Covid-19 Sunday, after being initially identified as an asymptomatic carrier last Tuesday, according to the Jilin provincial health commission. China records asymptomatic infections separately from its official case count.
Over four days, the man held four “health seminars,” or marketing sessions, in community health clubs targeting elderly residents in the cities of Gongzhuling and Tonghua in Jilin.
All the infected people had been tracked down as close contacts of the man and placed under quarantine, before testing positive during medical observation, Zhang said.
Although an effective tool for contact tracing, publicizing detailed travel history of coronavirus patients has also led to concerns around privacy in China.
Community health clubs under scrutiny
Jilin’s apparent superspreading event has brought community health clubs under greater scrutiny from health experts and authorities.
“The infected people were gathered in an enclosed space for a long time,” Zhao, the Jilin health official, told Xinhua. “Most of them are middle-aged and elderly people with underlying health conditions and weak immunity, and therefore extremely susceptible to infection.”
So-called “health clubs” catering to the elderly are becoming increasingly common among residential communities in China, where marketing sessions, often branded as “health lectures,” are regularly held to promote health products such as supplements and physical therapy equipment.
Unlike cinemas, restaurants, karaoke parlors and other commercial venues, these clubs are often hidden in residential buildings and difficult for authorities to regulate, according to Xinhua.
Jilin authorities are investigating whether the two health clubs where the man held promotions had violated any regulations, a provincial market supervision official said at the news conference.