Asymptomatic Covid-19 carriers can be the source of many contagions, a study finds. A woman carrying the coronavirus but showing no symptoms traveled for 60 seconds in an elevator in China and infected 71 people.
A new study published by the United States Centers for Disease Control (CDC) reveals how infectious the coronavirus can be. Researchers analyzed the impact that a single infected traveler, symptomless itself, may have on others, relates news.com.au.
A woman with no symptoms of Covid-19 climbed alone in an elevator in China, then 71 people were infected. However, she had done everything correctly. Although asymptomatic, she observed quarantine after a trip to the United States, remaining confined to her apartment and ordering food at home.
A thorough investigation
Investigators found it difficult to screen this woman, who became source of massive contamination. The story goes back to April 2, when a man from Heilongjiang Province who is suspected of being among the first to be infected, suffered a severe stroke, which is a possible known symptom of the disease in question, but has not been diagnosed. He was hospitalized urgently and his three sons took turns with him.
Without realizing it, they infected 28 other people, including five nurses and a doctor. Before being diagnosed, the patient was taken to a second hospital, where he caused 20 other infections. It was not until then that the alarm was triggered, according to the study.
Another man (patient B), who had contact with the stroke victim, had symptoms of Covid-19. All of his close contacts were tested and also proved positive. Immediately, all persons with whom the patient had been in contact were tested and placed in confinement. But some of them had spread the virus even further.
The investigators tried to understand the routes of contamination. Patient B had met the stroke victim and his sons at a party on March 29, but no one else among the guests was positive. They tested Patient B’s girlfriend, who turned out positive, as well as his daughter with whom she lived.
The danger of public places
The man visited them on March 26, but neither the mother nor the daughter had traveled or had any traveling contacts. The investigators therefore analyzed the movements of all those who lived in the same building as the first known victims. One of them, who lived above the woman and her daughter, had just traveled to the United States, they found.
A rapid assessment revealed that she was fine and that she followed the containment protocol. An analysis also showed that she had antibodies to Covid-19. However, the three women had not come into direct contact with each other. But they used the same elevator.
The researchers therefore concluded that the person from the United States was an asymptomatic carrier and that the girl had been infected by contact with the surfaces of the elevator. “Our results illustrate how a single asymptomatic SARS-CoV-2 infection could lead to widespread transmission”, estimated the authors of the study.