According to epidemiologic data published on the website of the Health Commission of Heilongjiang Province for April 2020, a woman returning from the United States who tested positive for coronavirus infected at least 71 people in China. In a research published in the US Centres for Disease Control and Prevention's journal Emerging Infectious Diseases, the April outbreak of Covid-19 in Heilongjiang Province, China was spread by asymptomatic US returnee who shed the virus in the elevator in her building.
On March 19, 2020, the woman was asked by the health officials to quarantine at home. While the woman had no close contact with any individual, the researchers noted that the disease was contracted by individuals who used the same contaminated elevator in the building. As per the Centres for Disease Control and Prevention’s report, a man with no relation to the asymptomatic woman, later suffered a stroke as he had been at a party with relatives of a neighbour who were living in the same building. The neighbour’s relatives had all later tested positive to the novel coronavirus having got the virus from the same elevator which was used by the woman’s mother and her boyfriend who had stayed with her a day earlier.
Researchers found that the two sons of the man infected at the party had also tested positive. Later, at least 28 people were infected at the first hospital where he was initially admitted, and 20 more got the coronavirus when he was moved to a second facility. The contagion so strong led the researchers to study the genome of the virus which revealed that the strain was a different one than previously detected in China when the outbreak started Hubei province. Researchers, according to the study, designated another woman in the neighbourhood as case-patient A0 who had returned from the US. Upon observation, experts found that while the patient A0 was not infected at the time, she had antibodies to the virus, meaning she was infected earlier and had recovered.
Researchers wrote in the study, “we believe A0 was an asymptomatic carrier and that B1.1, her neighbour, was infected by contact with surfaces in the elevator in the building where they both lived. Other residents in the building all tested negative. "Further, the researchers concluded, “All persons in this cluster, including those who lived in the same community and had close contact with SARS-CoV-2–positive patients. As of April 22, 2020, A0 remained asymptomatic, and a total of 71 SARS-CoV-2–positive cases had been identified in the cluster.”
(Image Credit: CDC)