Covid-19: Woman infects 71 people in building after using apartment lift

The asymptomatic woman tested negative when she returned from her trip but was told to self-isolate in her house.

A Chinese woman with no symptoms of Covid-19 unintentionally infected 71 people likely after using the elevator in her apartment block.   

According to reports in the Independent, the woman had returned to her home in Heilongjiang province, China, after a trip to the US on March 19. In an article published by the Centers for Disease Control and Prevention (CDC), it was stated that the woman returned eight days after the area last reported any new Covid-19 cases.
Researchers believe that the woman, whose identity has been protected in the report, contaminated the elevator in her building which in turn infected at least 71 people.
The asymptomatic woman tested negative when she returned from her trip but was told to self-isolate in her house. Although she had not taken the lift with anyone else, her downstairs neighbour is thought to have contracted the virus after he used the lift at some point after her.
The neighbour then infected her mother and mother's boyfriend when they visited her home to attend a party with another group of people. There, a stroke patient and his two sons who were at the party tested positive for the coronavirus. Researchers discovered the father was admitted to hospital where he and his two sons infected 28 people, including five nurses and one doctor. They went on to infect another 20 people in the second hospital.
When investigators tested the woman who travelled from the US again, they found she had antibodies which suggested that she had previously had Covid-19.

Following the mass infection in the residential building, researchers from the Chinese CDC wrote, "We believe [the traveller] was an asymptomatic carrier and that [the downstairs neighbour] was infected by contact with surfaces in the elevator in the building where they both lived.

They added, "Our results illustrate how a single asymptomatic Sars-CoV-2 infection could result in widespread community transmission."