Details of the case emerged in a new study published by the United States Centers for Disease Control (CDC) which analyzed the possible impact of a single traveler without symptoms, reports the Daily Star.
The cause of this case dates back to April 2, when a man in Heilongjiang Province suffered a severe stroke – a possible known symptom of the disease – but was not diagnosed, reports news.com.au .
The man was rushed to hospital and his three sons took turns with him. Between them, however, they unconsciously infected 28 other people, including five nurses and a doctor.
Before being diagnosed, the patient was transferred to another hospital, where 20 other people were infected.
Meanwhile, another man, known as Patient B, reported symptoms of Covid-19 and scientists discovered that the strain came from abroad.
All close contacts of patient B were tested and they were also positive – one of them was a stroke victim.
All those with whom the patient had been in contact, or even close to him in hospitals, were tested and detained, but almost 50 of them had already contracted the virus, some had transmitted it even more far.
The contact tracers tried to work backwards to find out how the patients had contracted the disease.
Patient B had met the stroke victim and his sons at a party on March 29, but no one else present was positive for the virus.
The man’s girlfriend was tested and it was discovered that she and the daughter had the virus. However, no other cases of Covid-19 could be linked to them.
The contact tracers called up the profiles of all the people living in the same residential building as the first known victims.
One had recently traveled from the United States – and she lived upstairs above the woman and her daughter. An evaluation found that she had followed the self-isolation protocol, but a swab showed that she had Covid-19 antibodies.
Detailed monitoring of the movements showed that the women had not come into direct contact with each other, which left only one possible source of contagion.
But they discovered that the asymptomatic traveler had used the elevator to the apartment where she had self-isolated.
“Therefore, we believe that A0 (the traveler from the United States) was an asymptomatic carrier and that B1.1 (the girl) was infected by contact with surfaces in the elevator of the building where they both lived. “Wrote the researchers.
“Our results illustrate how a single asymptomatic SARS-CoV-2 infection could lead to widespread community transmission,” concluded the study authors.
Researchers believe the girl must have touched her face, eyes or nose after using the buttons or pressing against the elevator panels.
They say their results reinforce the importance of hand washing and isolation to prevent the spread of the coronavirus.
“Continued measures to protect, screen and isolate those infected are essential to mitigate and contain the Covid-19 pandemic,” said the study.