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Posts misrepresent CDC study examining mask use

October 14, 2020 GMT

CLAIM: The Morbidity and Mortality Weekly Report by the U.S. Centers for Disease Control and Prevention shows that the majority of people who get sick with COVID-19 wear masks. 

AP’S ASSESSMENT: Missing context. Masks are designed to prevent the spread of the virus by the person wearing it and some studies have shown that masks can offer some protection to those who wear them. 

THE FACTS: Posts misrepresenting CDC figures from the report have gained millions of views on Facebook this week, falsely suggesting that masks are failing to protect people from COVID-19. 


The September report, which examines the behavior of coronavirus patients before their diagnosis, revealed that those who tested positive were twice as likely to have dined at a restaurant. Rather than share key findings from the study, posts online incorrectly suggested that wearing masks makes you more likely to contract the coronavirus and that not wearing one would keep you from catching it.

“If you look at the numbers from the CDC, of people that actually got COVID in this sample, 70.6% of them ALWAYS wore a mask,” stated one tweet, linking to numbers in the study. “And 3.9% NEVER wore a mask.”

Social media users zeroed in on the 71 percent figure in their posts ignoring other findings. Notably, in the 14-days before testing positive, 71 percent of patients reported using a cloth face covering or mask while 74 percent of people who tested negative also wore masks.

The posts were shared millions of times across social media platforms from Facebook, Instagram and Twitter. Fox News host Tucker Carlson also commented on the data in his show Tuesday and shared the CDC’s report on Facebook. 

A majority of studies have shown that wearing masks reduces the transmission of the virus by blocking respiratory droplets. Several studies have also shown that masks could offer some protection for the people who wear them. 

“We all know masks don’t provide perfect protection,” said Dr. William Schaffner, an infectious-diseases expert at Vanderbilt University. “What this emphasizes is not only do you have to wear a mask but so does everybody else.” 

The report looked at how people who tested positive for the virus were exposed. The group, made up of people over the age of 18, were tested at 11 outpatient health care facilities. Patients were asked whether they “always, often, sometimes, rarely or never” wore cloth face coverings or masks before the onset of their illness. 


“One of the things you have to assume here is that everyone is answering honestly and that the case patients are not biased in favor of saying ‘yes I know I was positive and will tell everyone I was wearing a mask anyway,’” Schaffner said. 

The study found that about half of all participants reported shopping and visiting others inside a home before their symptoms occurred and that adults with confirmed cases were about twice as likely to have reported eating at a restaurant before their diagnoses. 

The study included five factors that could have impacted the responses, among them that patients were aware of their test results “which could have influenced their responses to questions about community exposures and close contacts.”

In response to the posts, the CDC said in a statement to The Associated Press that in the case of the report it is difficult to detect the effect of an exposure or intervention like masks when it is being widely used. 

“Both cases and controls in the study had high levels of mask use,” the CDC said. “They were likely achieving sufficient protection within their social network.  However, in restaurants and other places where food and beverages are consumed, masks cannot be used.”


This is part of The Associated Press’ ongoing effort to fact-check misinformation that is shared widely online, including work with Facebook to identify and reduce the circulation of false stories on the platform.

Here’s more information on Facebook’s fact-checking program: