The presence of asymptomatic or asymptomatic transmission of disease makes tracking communication more difficult
A study of seven groups in Singapore conducted by Vernon J. Lee and others from the Singapore Ministry of Health, provides some evidence that transmission of the virus to others (which leads to infection) can occur from one to three days before symptoms appear on a person. But the World Health Organization confirms that the risk of developing a new coronavirus (SARS-CoV-2) from a person with Covid19 symptoms at all is “very low”. It says it is evaluating ongoing research on the duration of the virus.
Transmission of the disease was seen one to three days before symptoms appeared in four groups, while in three groups the exact timing of transmission was not determined as the condition of the indicator and contacts lived together. The results are published in the weekly morbidity and mortality report.
Early detection, patient isolation, and contact tracking are important to contain the spread of the virus. However, the presence of asymptomatic or asymptomatic transmission adds a new layer of complexity and challenge in tracking communications.
The first cases were confirmed in Singapore on January 23, and from January 23 to March 16, 243 cases were reported, of which 157 were referred locally. Of the 157 local transmission cases, 10 (6.4%) were recorded during the period before the symptoms on the person who spread the virus to others, and were therefore symptomatic.
Evidence from China
This is not the first case in which symptoms have been transmitted.
According to the Los Angeles Times, a 150-minute chorus training in Washington on March 10 as 60 people participated, leaving 45 people infected with the virus. Two died from COVID-19. The district health officials concluded that “the virus is transmitted through the air of one or more people without symptoms.”
Likewise, transmission of the virus was documented before symptoms at a nursing center in Kind County, Washington.