WHO Says It’s ‘Rare’ For An Asymptomatic Person To Spread Coronavirus

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World Health Organization (WHO) officials said Monday that it’s rare for infected people without symptoms to spread the coronavirus, according to CNBC. 

The possibility of people who have coronavirus but don’t have any symptoms transmitting the virus to others influenced policies like mask requirements and strict social distancing measures. 

Questions have been raised in recent weeks about the idea that coronavirus is spread by asymptomatic carriers. A Chinese study in late May found that asymptomatic coronavirus patients were contagious for a shorter period of time than patients with symptoms. Now, the head of WHO’s diseases and zoonosis unit Dr. Maria Van Kerkhove said Monday that asymptomatic spread is “very rare.”

“From the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual,” she said according to CNBC

“What we really want to be focused on is following the symptomatic cases,” she said, adding that if we would “drastically reduce the outbreak if we isolated symptomatic coronavirus patients and used contact tracing to isolate individuals that had been in contact with the patient. (RELATED: Study: Coronavirus Might Have Hit China ‘Late Summer’ Or ‘Early Fall’)

“We have a number of reports from countries who are doing very detailed contact tracing,” she said. “They’re following asymptomatic cases. They’re following contacts. And they’re not finding secondary transmission onward. It’s very rare.”

She noted that some studies have shown evidence of asymptomatic spread in nursing homes or within a household, but that more research is needed.

Accounting for the possibility of presymptomatic or asymptomatic transmission was a major influence on policies put in place to control the pandemic. 

The CDC said in early April that presymptomatic transmission “increases the challenges of containment measures,” and that “public health officials conducting contact tracing should strongly consider including a period before symptom onset to account for the possibility of presymptomatic transmission.”

“The potential for presymptomatic transmission underscores the importance of social distancing, including the avoidance of congregate settings, to reduce COVID-19 spread,” the CDC report read. “These findings suggest that to control the pandemic it might not be enough for only persons with symptoms to limit their contact with others because persons without symptoms might transmit infection.”