COVID-19 can be transmitted by people without symptoms

After more than a year of advising strict COVID-19 safety guidelines, the U.S. Centers for Disease Control and Prevention announced May 14 that fully vaccinated individuals can resume most regular activities without wearing masks or social distancing. 

Many people, including President Joe Biden, viewed the news as a positive sign, but some social media users interpreted the change differently. 

"This week we learned the CDC lied about outdoor transmission, which helped shape COVID prevention measures across states," reads one Instagram post. "What makes anyone think they haven’t lied about almost everything including transmission by asymptotic people, aka healthy people."

The caption on the post — which again erroneously uses the mathematical term "asymptotic" instead of the medical term "asymptomatic" — continues: "Transmission by asymptotic people has never been proven, which is how they shaped the entire policy around this issue." 

The post was flagged as part of Facebook’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Facebook.)

Setting aside the improper terminology, the post’s claim is false.

Studies have found that COVID-19 can be spread by people who are asymptomatic and do not show any symptoms of the disease. 

In a June 2020 interview on "Good Morning America," Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, estimated that 25% to 45% of "of the totality of infected people likely are without symptoms."

During the same interview, Fauci said, "we know from epidemiological studies" that asymptomatic people can transmit the virus "to someone who is uninfected even when they’re without symptoms."

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While not all researchers agree on exactly how or how frequently asymptomatic transmission happens, multiple studies have concluded that it does happen. 

A study conducted in Singapore from January to March 2020 found that presymptomatic transmission was responsible for several clusters of COVID-19 cases. For the purposes of the study, presymptomatic transmission was defined as "the transmission of SARS-CoV-2 from an infected person (source patient) to a secondary patient before the source patient developed symptoms ...with no evidence that the secondary patient had been exposed to anyone else with COVID-19."

Another study conducted at a skilled nursing facility in Washington found that "live coronavirus clearly sheds at high concentrations from the nasal cavity even before symptom development. Experts who analyzed the study concluded that the results indicated "that asymptomatic persons are playing a major role in the transmission of SARS-CoV-2."

Additional studies in The Journal of the American Medical Association, Science China Life Sciences, PLOS Medicine and Clinical Microbiology and Infection reaffirmed that asymptomatic transmission of COVID-19 occurs — though they generally conclude that it occurs less frequently than symptomatic or presymptomatic transmission. 

The updated CDC guidance is for vaccinated people. The CDC explained the change on its website: "A growing body of evidence suggests that fully vaccinated people are less likely to have asymptomatic infection and potentially less likely to transmit SARS-CoV-2 to others. However, further investigation is ongoing."

The CDC also cited a broader need to encourage vaccination in its rationale for changing masking and social distancing requirements for fully vaccinated people. It referenced a January 2021 Kaiser Family Foundation survey about COVID-19 vaccine hesitancy.

"Maintaining a requirement to continue all prevention measures after vaccination may disincentivize vaccine uptake," the CDC’s website says. "In a survey from January 2021, one in five people reported being less likely to get vaccinated if they heard that they will need to continue to wear a mask and practice social distancing even after getting vaccinated."

An Instagram post claimed that transmission of COVID-19 by people who are asymptomatic "has never been proven."

Multiple studies have found that asymptomatic transmission of COVID-19 occurs, though there is no consensus on how or how often it happens. 

We rate this claim False.