UAB study, among others, shows masks are effective in preventing spread of COVID-19

Studies conducted in America and around the world definitively show that masks are an effective tool in reducing the rate of injection of COVID-19.

Close-up of Jordan Lingo (Graduate Student, Microbiology) wearing a homemade fabric mask while standing outdoors during the COVID-19 (Coronavirus Disease) pandemic, April 2020.Studies conducted in America and around the world definitively show that masks are an effective tool in reducing the rate of injection of COVID-19.
(Photography: Lexi Coon)
Physicians at the University of Alabama at Birmingham say universal masking of health care workers at UAB Hospital led to an immediate reduction in risk of exposure to COVID-19 by 68 percent in the early days of the pandemic. In a study published in the journal Clinical Infectious Diseases in September 2020, the authors go on to say that universal testing further decreased those exposures by 77 percent. 

“At the very beginning of the pandemic as we saw an increase of cases at UAB, we decided to implement universal masking for all health care workers and all patients/visitors to UAB Hospital in March of last year,” said Rachael Lee, M.D., assistant professor in the Division of Infectious Diseases at UAB and the study’s senior author. “Now, 18 months into this pandemic, we have real-world observational data supporting the use of masks in both children and adults.”

In addition to the UAB study, Lee references a study from China that found that facemasks were 79 percent effective in preventing transmission in households. Another systematic review, sponsored by the World Health Organization, showed that physical distancing, facemasks and eye protection all reduce the risk of person-to-person transmission of COVID-19.  

“Because we are in a pandemic, it is difficult to perform randomized controlled trials, due to ethical reasons. However, we have strong observational data that show masks protect us and others from exposure and transmission of COVID-19 with minimal risks to the wearer,” Lee said.

Lee also reports that a study in North Carolina schools, authorized by the North Carolina legislature and conducted by the ABC Science Collaborative, through the Duke University Clinical Research Institute, demonstrated the effectiveness of masking. 

The authors of that study reported that the scientific analysis of the data provided directly from 100 school districts and 14 charter schools from March to June 2021, representing more than 865,000 students and 160,000 staff, showed that proper masking was the most effective mitigation strategy to prevent secondary transmission in schools when COVID-19 is circulating and when vaccination is unavailable or there is insufficient uptake. 

The study also showed that distance was not a factor in the spread of COVID-19 when students/staff/teachers are masked. Masking was adequate to prevent within-school COVID-19 transmission, with no difference between schools requiring greater than 3 feet of distance between students compared to those requiring less than 3 feet. 

Todd McCarty, M.D., assistant professor of infectious diseases at UAB, says numerous studies have shown that children are minimally affected by wearing facemasks.

“We have substantial observational data that all points in the same direction: that children fare well even while wearing masks in many of the socialization skills that are so important at a young age,” McCarty said.

McCarty offers four studies that bolster this argument: 

From side, father and son, William "Bill" Mayfield (Emergency Preparedness Manager, UAB Healthcare System) and Matthew Mayfield (Student, Public Health) are wearing homemade medical masks (made with material representing the 9/11 attacks) around their necks while standing in the UAB Hospital COVID-19 (Novel Coronavirus) Command Center, North Pavilion, April 2020.(Photography: Lexi Coon)“It is understandable that parents and other individuals are concerned about possible risks/harms of wearing masks,” McCarty said. “In all of the studies that have been done, these concerns have not been shown to have a measurable impact. While detractors point to the quality of data that supports the benefits of masking, that observational data still exceeds any study that has raised concern about risk. The balance of the data clearly shows benefits outweigh unknown or unsupported risks.” 

“Historically, we have seen the results of many randomized controlled trials of other respiratory viruses such as influenza, which spread via droplets similar to COVID-19,” Lee said. “In a Cochrane Review of 67 randomized controlled trials and observational studies looking at reducing transmission of respiratory viruses, masks were found to be the best at performing interventions across populations.”

“We now have countrywide, international-based data on the efficacy of wearing masks,” said Jeanne Marrazzo, M.D., director of the Division of Infectious Diseases at UAB. “The evidence is very persuasive that masks work in public to prevent community spread of transmission.”