Excessive-quality masks may forestall viral transmission and scale back COVID-19 deaths
Researchers from North Carolina State University and the Georgia Institute of Technology studied the effectiveness of wearing quality masks and face covers in preventing SARS-CoV-2 transmission. Their study entitled “High-quality masks can reduce infections and deaths in the USA” was published on the preprint server medRxiv *.
What was this study about?
Worldwide, over 35 million people are infected with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes the COVID-19 disease. This highly infectious virus has claimed over a million lives around the world to date.
In the United States, the number of cases has exceeded seven million, with over 210,000 people killing from COVID-19. The researchers on this study wrote that by August 2020, there was a higher prevalence of the infection in the US, particularly 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 discussed with several controversies and misunderstandings. Public health officials said wearing masks for a few weeks could help significantly stop and prevent the virus from spreading across the community. 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 infection from spreading within the community, and whether these face coverings could stop an outbreak once it is already in community transmission. They surveyed the urban, suburban, and rural counties to check the level of compliance with mask norms in the communities and the effectiveness of masks.
The prevalence of infectious people over time is shown. Subfigure (above) has cases of varying population conformity (0%, 40%, 60%, 80%, 100%) while mask effectiveness is 50%. Lower figure (below) shows cases with different mask effectiveness (20%, 40%, 60%, 80%, 90%), while the compliance of the population is 60%.
This was a prospective study. The team used a stochastic network simulation model to assess the progression of COVID-19 via the census tracts according to a variant of SEIR. The simulated situations in which the broadcast can occur in various environments such as homes, workplaces, and schools, as well as in communal settings.
They were considering a public health order about three and a half months ago urging the public to wear masks or face covers to prevent the infection from spreading. They used their analytical models to determine whether wearing masks reduced susceptibility and transmission of the infection by 50 or 80 percent. The chances of a person wearing a mask were 0, 20, 40, 60, 80, or 100 percent, the team wrote. The calculated infection rate was calculated using measures such as the cumulative infection attack rate (CAR), peak prevalence of infection, and population mortality. They took into account the reproduction rate (2.4 without interventions such as masks), the hospital stay and mortality rates based on age groups, the infection mortality rate, and the asymptomatic and symptomatic transmission coefficients (transmission rate of infection from symptomatic and asymptomatic persons).
Results of the study
The main highlights of the results were:
- At the start of the study, the infection attack rate without masks (0 percent masks) was 36 percent, the maximum infection rate 1.15 percent and the overall mortality 0.176 percent.
- When 60 percent of the public wore masks that were 50 percent effective, the Cumulative Infectious Attack Rate (CAR) decreased 25 percent
- When 60 percent of the population wore masks that were 50 percent effective, the peak infection prevalence dropped 51 percent
- When 60 percent of the population wore masks that were 50 percent effective, the population’s mortality or risk of death decreased by 25 percent
- When 100 percent of the population wore masks (or 60 percent masks that are 80 percent effective), the CAR dropped 38 percent
- When 100 percent of the population wore masks (or 60 percent masks that are 80 percent effective), the peak prevalence dropped 67 percent
- When 100 percent of the population wore masks (or 60 percent masks that are 80 percent effective), population mortality decreased by 40 percent
- The team concludes: “With every increase in compliance by 20 points (e.g. 60 percent compliance to 80 percent compliance), the IAR drops by approximately 2.47 points, the mortality rate drops by approximately 0.014 points, and the peak prevalence drops (14 ) -37 percent of the previous value) “
Conclusions and implications
The team writes that this study shows that it is also the quality of the masks that can make a difference. They urge people to switch from low-effectiveness face coverings such as “neck gaiters or bandanas” and to more effective masks such as “multiple layers of fabric or special filtration material such as N95 masks”.
The study authors stated, “Once communicated, masks can significantly reduce infection.” This study shows that, along with interventions such as distancing, closing some community meetings, and an effective vaccine, masks play an important role in preventing airborne transmission transmitted infection like COVID-19. They concluded, “Stopping the transmission after it has become widespread in the community requires multiple interventions at the same time.”
* Important NOTE
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be considered conclusive, guide clinical practice / health-related behavior, or treated as established information.