Update: As Breitbart News reported here, on June 9 the W.H.O. walked back its June 8 claim by Dr. Maria Van Kerkhove that asymptomatic spread of COVID-19 is “very rare,” stating that according to estimates based on models, asymptomatic spread could account for up to 40 percent of COVID-19 transmission. Van Kerkhove said it is a “really complex question,” and, “We don’t actually have that answer yet.” Both asymptomatic (defined by the W.H.O. as those who never develop any symptoms) and pre-symptomatic people (meaning those who have yet to show symptoms but will eventually) can appear healthy yet spread the disease.
Coronavirus patients without symptoms, or asymptomatic patients, are not the ones spreading the virus, the World Health Organization (W.H.O.) announced Monday.
The organization’s announcement comes at a time where some researchers shared concerns that the disease could be difficult to contain due to asymptomatic infectious people, CNBC reported.
Some people who are young and otherwise healthy who catch the coronavirus never develop symptoms or only develop mild symptoms. Other people might not develop symptoms until several days after they catch the infection.
Preliminary evidence showed that coronavirus could be spread from person-to-person contact, even if the carrier was asymptomatic, but now the W.H.O. is saying the coronavirus is not mainly spread through these asymptomatic people.
“From the data we have, it still seems to be rare that an asymptomatic person actually transmits onward to a secondary individual,” Dr. Maria Van Kerkhove, head of W.H.O.’s emerging diseases and zoonosis unit, said at a news briefing from the United Nations agency’s Geneva headquarters. “It’s very rare.”
Van Kerkhove said governments should focus on isolating people who are showing symptoms and tracking down anyone who may have come into contact with them. In other words, they are relying on contact tracing data.
“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.”
If asymptomatic spread proves not to be the main transmission of coronavirus, it could have huge impacts on policy. A Centers for Disease Control and Prevention (CDC) report from April 1 cited the “potential for presymptomatic transmission” as the reason for social distancing.
“These findings also 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,” the CDC study said.