High-quality masks could prevent viral transmission and reduce COVID-19 deaths

By Dr. Ananya Mandal, MDOct 5 2020

Researchers from North Carolina State University and Georgia Institute of Technology studied the effectiveness of wearing high-quality masks and face coverings for the prevention of SARS-CoV-2 transmission. Their study titled, “High-Quality Masks Can Reduce Infections and Deaths in the US,” was released on the preprint server medRxiv*.

What was this study about?

Over 35 million people worldwide have been infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes COVID-19 disease. This highly infectious virus has claimed over a million lives globally to date.

In the United States, the number of cases has crossed seven million, with over 210,000 lives lost due to COVID-19. The researchers in this study wrote that up until August 2020, in the USA, there has been a higher prevalence of the infection, especially in the South and Midwest.

Role of masks and face coverings

The team writes that the exact role of masks or face coverings has been debated with several controversies and misconceptions around it. Public health officials have said that wearing masks for a few weeks could help stop and prevent the spread of the virus in the community significantly. Masks can reduce the spread of the virus via droplets, they wrote.

The purpose of this study was to see how effective masks are in preventing the spread of the infection within the community, and if these face coverings could stop an outbreak when community transmission is already on. They studied the urban, suburban, and rural counties to check the level of adherence to mask norms among communities and the efficacy of wearing masks.

Prevalence of infectious people over time is shown. Subfigure (top) has cases with different levels of population compliance (0%, 40%, 60%, 80%, 100%) while mask effectiveness is 50%. Subfigure (bottom) has cases with different levels of mask effectiveness (20%, 40%, 60%, 80%, 90%) while population compliance is 60%.

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources

Study design

This was a prospective study. The team utilized a stochastic network simulation model to assess the progression of COVID-19 spread across the census tracts according to a variant of SEIR. The simulated situations where the transmission could occur in different settings such as households, workplaces and schools, and community settings.

They considered a public health order around three and a half months back that mandated the public to wear masks or face coverings to prevent the spread of the infection. They used their analysis models to assess if wearing masks reduced the susceptibility and transmission of the infection by 50 or 80 percent. The probability of an individual wearing a mask was 0, 20, 40, 60, 80, or 100 percent, the team wrote. The calculated the rate of infection using measures such as cumulative infection attack rate (CAR), peak prevalence of the infection, and population mortality. They considered reproductive rate (2.4 with no interventions such as masks), rates of hospitalization and mortality rates based on age groups, Infection Fatality Rate, and asymptomatic and symptomatic transmission coefficients (rate of transmission of the infection from symptomatic and asymptomatic individuals).

Results of the study

The main highlights of the results were:

• At baseline, with no persons wearing masks (0 percent masks), the Infection Attack Rate was 36 percent, the peak infection rate was 1.15 percent, and the overall mortality was 0.176 percent, they found.
• If 60 percent of the public wore masks that are 50 percent effective, the cumulative infection attack rate (CAR) fell by 25 percent
• If 60 percent of the public wore masks that are 50 percent effective, the peak prevalence of the infection fell by 51 percent
• If 60 percent of the public wore masks that are 50 percent effective, the population mortality or risk of death fell 25 percent
• If 100 percent of the population wore masks (or 60 percent wore masks that are 80 percent effective), the CAR dropped by 38 percent
• If 100 percent of the population wore masks (or 60 percent wore masks that are 80 percent effective), the peak prevalence fell by 67 percent
• If 100 percent of the population wore masks (or 60 percent wore masks that are 80 percent effective), the population mortality fell by 40 percent
• The team writes in conclusion, “For each 20 point increase in compliance (e.g., 60 percent compliance to 80 percent compliance), the IAR decreases by approximately 2.47 points, the mortality rate drops by approximately 0.014 points, and the peak prevalence decreases (14-37 percent of the previous value)”

Conclusions and implications

The team writes that this study shows that it is also the quality of masks that can make a difference. They urge people to shift from low efficacy face coverings such as “neck gaiters or bandanas,” and move to effective masks such as those with “multiple fabric layers or special filtration material like N95 masks”.

The authors of the study explained, “After community transmission is present, masks can significantly reduce infections.” This study reveals that apart from interventions such as distancing, closures of some community gatherings, and an effective vaccine, masks play a significant role in preventing transmission of an airborne infection such as COVID-19. They concluded, “To stop transmission after it is widespread in the community, multiple interventions will be needed simultaneously.”

This news article was a review of a preliminary scientific report that had not undergone peer-review at the time of publication. Since its initial publication, the scientific report has now been peer reviewed and accepted for publication in a Scientific Journal. Links to the preliminary and peer-reviewed reports are available in the Sources section at the bottom of this article. View Sources