A woman returning to China from the United States carried a coronavirus with her and spread an epidemic that infected at least one person, researchers said Tuesday.
It began with an elevator ride, researchers report in the Journal of Disease Control and Prevention at Emerging Infectious Diseases Centers.
The woman traveled to the United States on March 19 and returned to Heilongjiang province, about a week after the latest coronavirus case was detected in the province. He had no symptoms and tested negative for the coronavirus, but was told to isolate at home.
No one suspected that anything was wrong until a man without a clear connection to the passenger suffered a stroke. It turns out that he was at a party with relatives of a neighbor who lived in the same building as the traveler.
When Chinese researchers finally put the story together, they determined that the traveler must have somehow contaminated the elevator in his building. Her neighbor below, who used the same elevator, also became infected and as a result she infected her mother and her mother’s boyfriend. They go to a party and infect a stroke patient and her boys.
The stroke patient and his two sons went to two hospitals. At least 26 people were infected at the first hospital and another 20 were infected when he was transferred to the second hospital.
When the Chinese Center for Disease Control and Prevention investigated the genetic makeup of the virus found in this new outbreak, they found that it was different than the strain seen before in China. The patients’ viruses were genetically identical or at least very similar, which led them to believe that the virus had originated abroad.
When investigators learned that a neighbor in the case had recently returned from abroad, they examined him again. He was not currently infected but had antibodies to the virus, indicating a previous infection. They nominated him A, which means he is the first case. “Thus, we believe that A0 was an incomplete carrier and B1.1 (its neighbor) was exposed to the surface of the elevator in the building in which they both lived,” they wrote. The other occupants of the building all tested negative.
“As of April 22, 2022, A0 was synthesized and a total of S1 SARS-CoV-2-positive events were detected in the cluster,” the researchers wrote.
“Our results explain how a single asymptomatic SARS-CoV-2 infection can lead to widespread community infections.”