Experts Suggest Nearly Half of Those with Coronavirus Could be Asymptomatic

We’re hearing it everywhere: those with the virus might not exhibit symptoms. Here’s what you should know about the word asymptomatic—and the risks.

Last week, the CDC, along with President Trump, issued a new face-mask guidance, encouraging people to wear cloth face coverings when in public. While nothing can be too certain, there is mounting evidence that the virus may be transmissible through the air, and recent studies suggest a huge number of individuals with the virus may lack symptoms.

Lacking symptoms does not mean a decreased likelihood of passing on the virus. Far from it. Elected officials across the globe have stressed the importance of staying home and social distancing—largely to protect essential workers who can’t. While there’s a lot up in the air about the virus, here’s what we know about the virus and those who are asymptomatic.

What does asymptomatic mean?

If you are truly asymptomatic, that means you are infected with the virus, but you never exhibit symptoms of the disease. For the coronavirus, those symptoms are often dry cough, fever and fatigue. However, those who are asymptomatic are still contagious.

How many people with the virus are asymptomatic?

In this area, researchers don’t really how. However, recent studies (like one in Iceland) reported that as many as 50 percent of cases could be asymptomatic. An analysis of the confirmed coronavirus cases aboard the Diamond Princess cruise found that 18 percent of the infected passengers were asymptomatic. Last week, CDC director Dr. Robert Redfield estimated that 25 percent of people with the virus may be asymptomatic. The National Institute of Allergy and Infectious Diseases director Dr. Anthony Fauci estimated that 25 to 50 percent of cases may be asymptomatic.

Is it possible that some people who were asymptomatic when they were tested later showed symptoms?

The short answer: yes. Dr. Maria Kerkhove, head of the emerging disease and zoonoses unit at the World Health Organization, said she thinks that many cases have been misclassified as asymptomatic, when in fact they were “presymptomatic” (people who are presymptomatic have no symptoms when they test positive but go on to develop symptoms).

“Most of the people who were thought to be asymptomatic aren’t truly asymptomatic,” she said. “When [WHO] went back and interviewed them, most of them said, ‘Actually, I didn’t feel well, but I didn’t think it was an important thing to mention. I had a low-grade temperature, or aches, but I didn’t think that counted.’”

For a comprehensive look at a number of studies that have measure the number of asymptomatic individuals, check out the Center for Evidence-Based Medicine's article. Based on a number of studies, they predict anywhere from five to 80 percent of individuals could be asymptomatic with the virus.

The bottom line though, symptoms or no symptoms, is that “there are people out there spreading the virus who don’t know that they’re infected,” said Dr. Jeffry Shaman to the New York Times.

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