JAMA editorial reviews latest science, while case study shows masks prevented COVID spread
Americans are increasingly adopting the use of cloth face masks to slow the spread of COVID-19, and the latest science may convince even more to do so.
In an editorial published today in the Journal of the American Medical Association (JAMA), CDC reviewed the latest science and affirms that cloth face coverings are a critical tool in the fight against COVID-19 that could reduce the spread of the disease, particularly when used universally within communities. There is increasing evidence that cloth face coverings help prevent people who have COVID-19 from spreading the virus to others.
“We are not defenseless against COVID-19,” said CDC Director Dr. Robert R. Redfield. “Cloth face coverings are one of the most powerful weapons we have to slow and stop the spread of the virus – particularly when used universally within a community setting. All Americans have a responsibility to protect themselves, their families, and their communities.”
This review included two case studies out today, one from JAMA, showing that adherence to universal masking policies reduced SARS-CoV-2 transmission within a Boston hospital system, and one from CDC’s Morbidity and Mortality Weekly Report (MMWR), showing that wearing a mask prevented the spread of infection from two hair stylists to their customers in Missouri.
Additional data in today’s MMWR showed that immediately after the White House Coronavirus Task Force and CDC advised Americans to wear cloth face coverings when leaving home, the proportion of U.S. adults who chose to do so increased, with 3 in 4 reporting they had adopted the recommendation in a national internet survey.
The results of the Missouri case study provide further evidence on the benefits of wearing a cloth face covering. The investigation focused on two hair stylists — infected with and having symptoms of COVID-19 — whose salon policy followed a local ordinance requiring cloth face coverings for all employees and patrons. The investigators found that none of the stylists’ 139 clients or secondary contacts became ill, and all 67 clients who volunteered to be tested showed no sign of infection.
The finding adds to a growing body of evidence that cloth face coverings provide source control – that is, they help prevent the person wearing the mask from spreading COVID-19 to others. The main protection individuals gain from masking occurs when others in their communities also wear face coverings.
COVID-19 prevention in a Missouri hair salon
When two stylists at a Missouri hair salon tested positive for the virus that causes COVID-19, researchers from CoxHealth hospitals, Washington University, the University of Kansas, and the Springfield-Greene County Health Department worked together to trace contacts, investigate the cases, and publish their findings in the MMWR.
One ofthe stylists developed respiratory symptoms but continued to see clients for eight days. The other, who apparently became infected from her co-worker, also developed respiratory symptoms and continued to see clients for four days.
The salon in which they worked had a policy requiring both stylists and their clients to wear face coverings, consistent with the local government ordinance. Both stylists wore double-layered cloth face coverings or surgical masks when seeing clients. The median appointment time was 15 minutes and ranged from 15 to 45 minutes. More than 98% of clients wore a face covering—47% wore cloth face coverings, 46% wore surgical masks, and about 5% wore N-95 respirators.
When customers were asked whether they had been ill with any respiratory symptoms in the 90 days preceding their appointment, 87 (84%) reported that they had not. None of the interviewed customers developed symptoms of illness. Among 67 (48%) customers who volunteered to be tested, all 67 tested negative for the virus that causes COVID-19. Several family members of one of the stylist’s subsequently developed symptoms and received a diagnosis of COVID-19.
Survey: Acceptance of face-mask guidance increased
CDC analyzed data from an internet survey of a national sample of 503 adults during April 7–9 and found that about 62% said they would follow the newly announced recommendations to wear a face mask when outside the home. A repeat survey during May 11-13 showed that the percentage of adults endorsing face mask wearing increased to more than 76%.
The increase was driven largely by a significant jump in approval by white, non-Hispanic adults, from 54% to 75%. Approval among Black, non-Hispanic adults went up from 74% to 82%, and remained stable among Hispanic/Latino adults at 76% and 77%.
There was also a large increase in face-mask approval among respondents in the Midwest, from 44% to 74%. Approval was greatest in the Northeast, going from 77% to 87%.
- CDC’s Information on Cloth Face Coverings: https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/diy-cloth-face-coverings.html
- CDC Editorial in JAMA: Brooks JT, Butler JC, Redfield RR. Time for universal masking and prevention of transmission of SARS-CoV-2. JAMA. Published online July 14, 2020. doi:10.1001/jama.2020.13107 https://jamanetwork.com/journals/jama/fullarticle/10.1001/jama.2020.13107
- MMWR Article: No Transmission of Symptomatic SARS-CoV-2 After Significant Exposure With Universal Face Mask Use at a Hair Salon – Springfield, Missouri, May 2020 https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e2.htm?s_cid=mm6928e2_w
- MMWR Article: Factors Associated with Cloth Face Coverings Use during the COVID-19 Pandemic — United States, April and May 2020 https://www.cdc.gov/mmwr/volumes/69/wr/mm6928e3.htm?s_cid=mm6928e3_w