Researchers reported on Tuesday that a woman who returned to China from the United States carried the coronavirus back and caused an outbreak that eventually infected at least 71 people.
The researchers reported in the “Emerging Infectious Diseases” magazine of the Centers for Disease Control and Prevention that it started with the elevator.
The woman traveled back to Heilongjiang Province from the United States on March 19, about a week after the last coronavirus case in the province was diagnosed. She had no symptoms and the coronavirus test was negative, but was asked to be quarantined at home.
Before a man who had no obvious contact with a traveler had a stroke, no one doubted what was wrong. It turns out that he once attended a party with relatives of a neighbor who lived with travelers.
When Chinese researchers finally put the story together, they determined that the traveler must somehow contaminated the elevator in her building. Her neighbor downstairs (using the same elevator) was also infected, and then infected her mother and her boyfriend. They attended a party and contracted the stroke patient and his son.
The stroke patient and his two sons went to two hospitals. When he was transferred to the second hospital, at least 28 people were infected in the first hospital, and more than 20 people were infected.
When the Chinese Center for Disease Control and Prevention investigated the genetic makeup of the virus found in the new epidemic, they found that the virus was different from the virus previously found in China. The viruses in patients are genetically identical or at least very similar, which leads them to believe that the virus originated overseas.
When investigators learned that the neighbor of one of the cases had recently returned from abroad, they tested her again. She is not currently infected, but has anti-viral antibodies, indicating that she had been infected previously. They designate her as A0, which means that she is the first case. They wrote: “So we think A0 is an asymptomatic carrier, and B1.1 (her neighbor) was infected by contact with an infection on the elevator surface in the building where they both live.” Others in the building Residents tested negative.
The researchers wrote: “As of April 22, 2020, A0 remained asymptomatic, and a total of 71 SARS-CoV-2 positive cases were identified in this group.”
“Our results show how a single asymptomatic SARS-CoV-2 infection can cause widespread community transmission.”