RIO DE JANEIRO, BRAZIL – In a marked departure from previous lukewarm notices on surface-to-person transmission, the United States Center for Disease Control and Prevention, CDC, published this month a peer-reviewed research letter reporting a large outbreak of COVID-19 infections that they hold began by contact with surfaces in an elevator in a province in China that had not reported a new COVID-19 diagnosis since March. Now the agency says people need to adjust their behavior to protect themselves as new information comes available.
It was an infected but asymptomatic woman alone in an elevator who did not come into close contact with anyone, but was responsible for a COVID-19 outbreak that infected 71 people, reports the research letter tracking and analyzing coronavirus disease and highlighting the ease of COVID-19 spread. Neighbors were infected by contact with surfaces in the elevator in the building where they lived and they went on to infect other people, believe the authors of the report after an extensive case investigation summarized here.
According to the report, the woman’s short trip by the elevator to her apartment block on the way to quarantine may have been the factor behind the outbreak. The asymptomatic woman returned from the US to the Chinese province of Heilongjiang in March. When tested, she presented a negative result, but, as an international traveler, she was required to quarantine in her home, where she lived alone. As it turned out, she was also alone in the elevator when she went to the apartment and did not come into close contact with anyone during the quarantine.
The authors of the study — Jingtao Liu of Hubei University of Medicine in Shiyan, China; Jiaquan Huang of the Huazhong University of Science and Technology in Wuhan; and Dandan Xiang Tongji Hospital in Wuhan — found that the neighbor downstairs from the woman’s apartment used the same elevator. That neighbor’s mother and boyfriend, then spent the night in the apartment, and later interacted with another man and his two children. This other man suffered a stroke in early April and was admitted to a hospital, his two children by his side. During the time he was in the hospital, he was treated by a medical team who was also in charge of other patients in the ward. When the man developed a fever and was transferred to another hospital.
“Prior to April 9, 2020, Heilongjiang Province, China, had not reported a new COVID-19 diagnosis since March 11, 2020. On April 9, SARS-CoV-2 was diagnosed in 4 patients. By April 22, more than 71 persons had been infected. The likely origin of this cluster is an imported case from an asymptomatic traveler,” says the CDC report. We had a Patient Zero.”
Experts noticed the connection when the mother of Patient Zero’s neighbor and her boyfriend developed symptoms and tested positive. Things came into focus when the neighbor, the neighbor’s mother and the man who had a stroke, all tested positive.
The stroke hospitalization resulted in the infection of 28 others, included other ambulatory patients and the medical team. Objects, such as tomography equipment and a microwave, were also shared with other patients. The transfer to a second hospital resulted in another 20 infections.
It was only on April 9, exactly three weeks after the woman returned to China, that investigators established their link. Although the woman’s test was negative, a subsequent antibody test had positive results, which is an indicator that she had already been infected, meaning she was an asymptomatic carrier.
The man with the stroke tested positive on April 9 and was quarantined. The epidemiologic investigation showed that none of these people had a history of travel or residence in affected areas with sustained transmission of COVID-19 during the 14 days before diagnosis, says the report, suggesting that the infection came from contact with other persons: four patients were infected in other wards and the tomography room of the first hospital along with one doctor and 5 nurses. Twenty others were infected in the second hospital.
“On April 15, the Chinese Center for Disease Control and Prevention sequenced the entire genomes of 21 samples from the cluster,” reported the authors. “Viral genomes were identical in 18 cases and 3 other cases had a difference of 1–2 nucleotides, indicating that SARS-CoV-2 came from the same point of origin. The viral genome sequences from the cluster were distinct from the viral genomes previously circulating in China, indicating the virus originated abroad and suggesting [Patient Zero] was the origin of infection for this cluster.”
Just a month ago, the CDC said on its website “COVID-19 is thought to spread mainly through close contact from person-to-person. Some people without symptoms may be able to spread the virus” adding only speculatory warnings about surface transfer: “Based on data from lab studies on COVID-19 and what we know about similar respiratory diseases, it may be possible that a person can get COVID-19 by touching a surface or object that has the virus on it and then touching their own mouth, nose, or possibly their eyes, but this isn’t thought to be the main way the virus spreads.”
The CDC report, “Large SARS-CoV-2 outbreak caused by asymptomatic traveler, China.” Emerg Infect Dis. 2020 Sep., holds that this outbreak began by people touching surfaces in an elevator, moving beyond a mere possibility, and rendering surface or object transmissions a reality and a new concern.
While coronavirus is a generic term that includes a large family of viruses, using it as a descriptor is as broad as saying someone has the flu without identifying its strain as, say N1H1. As far as virus nomenclature is concerned, SARS-CoV-2 is the specific virus that can cause COVID-19. It might help to think of it in the same way that HIV is the virus that causes AIDS or rubeola causing measles. The clinical spectrum of COVID-19 ranges from asymptomatic to severe pneumonia with respiratory failure and death.
CDC guidelines say that SARS-CoV-2 may remain viable for hours to days “on surfaces made from a variety of materials,” recommending cleaning and disinfection of visibly dirty and frequently touched surfaces as a best measure of prevention against COVID-19
The report on the CDC website moves surface-to-person transmission from the merely speculative possibility to peer-reviewed notice and alarm, highlighting the resources required for case investigation.
Referring to the case held to be the source of the outbreak through transmission by touching an elevator surface, the report concluded, “Our results illustrate how a single asymptomatic SARS-CoV-2 infection could result in widespread community transmission,” and recommended “continued measures to protect, screen, and isolate infected persons are essential to mitigating and containing the COVID-19 pandemic.”