Ask an Epidemiologist: Why are indoor mask requirements in place?

Epidemiologist and Elon Assistant Professor Joann Gruber offers a look at the science behind indoor mask requirements at Elon and elsewhere and explains how masks can combat COVID-19.

Elon University along with other colleges and universities across the country has instituted policies designed to promote health and safety on campus during the COVID-19 pandemic. As the pandemic has evolved, so have campus requirements, with Elon instituting a mask requirement for indoor spaces leading up to the beginning of the Fall Semester.

Joann Gruber, assistant professor of public health studies

That requirement remains in place amid a surge in cases in Alamance County, the region and the country due to the Delta variant of the virus. Taken together, COVID-19 vaccinations and mask requirements can help stem an increase in transmission of the virus, and help keep close-knit communities such as Elon University as safe as possible.

So what role do masks play in this? Joann Gruber, an epidemiologist and assistant professor of public health studies at Elon, offers insights into the role that masks play, why masks are needed in environments such as colleges and universities and why a variety of approaches is needed to fight the spread of the virus.

How is COVID-19 spread and how do masks help prevent that spread?

SARS-CoV-2, the virus that causes the disease COVID-19, is a respiratory virus. This means the infection is typically concentrated in your respiratory tract. The virus, which is extremely small, can spread to others through respiratory particles that we expel when we talk, breathe, sing, and yell. These particles are so small that we cannot see them with our naked eye.

Masks can help limit the respiratory particles expelled by a person who is infected and can help prevent people near that person from breathing in those particles. This is why masks are most effective when everyone is wearing them.

What makes college and university campuses unique environments when it comes to how viruses spread?

College and university campuses are what public health professionals call “high-density congregate settings” meaning there are many people living in close proximity to one another. This level of connectedness makes it easy for diseases that are transmitted from person-to-person to spread rapidly through the campus. The fact that college and university campuses having high potential for spreading SARS-CoV-2 was the very reason employees and students were prioritized for COVID-19 vaccines in early 2021.

Why are you more likely to see the spread of the virus in indoor spaces rather than outdoors?

Because SARS-CoV-2 is a respiratory virus, ventilation is an important factor influencing the spread of disease.

Some very small respiratory particles we expel when we talk or breathe can stay suspended in the air indoors for hours. If there is no air movement (ventilation) to force those particles to move or be diluted, someone may breathe in those small particles and become infected. By contrast, when we are outdoors, fresh air can move and dilute those respiratory particles. This helps reduce the likelihood that someone will breathe in enough virus to cause an infection.

If you’re indoors, it is a great idea to open the door and/or windows to increase ventilation. If you’re outdoors, it is still a good idea to physically distance and wear a mask if there are many people close together.

Elon has a high vaccination rate among students, faculty and staff. Does that mean the virus is less likely to spread among the campus community?

Yes and no. Vaccinated people are less likely than unvaccinated people to become infected with SARS-CoV-2. That means the virus is less likely to spread at Elon than if we had low vaccination rates. However, respiratory viruses, like SARS-CoV-2, can spread very easily in a college/university setting. Our current COVID-19 vaccines are highly effective at protecting people from severe disease and death from COVID-19. However, the vaccines are less effective at preventing mild or asymptomatic infection. This means that even vaccinated students, faculty, and staff can become infected and spread the virus to others.

What is the current public health guidance for fully vaccinated “close contacts” related to masks, testing, and quarantine?

The most current guidance from both the Centers for Disease Control and Prevention and the North Carolina Department of Health and Human Services states that asymptomatic fully vaccinated people should wear a mask indoors when they’re identified as a close contact of someone who tests positive for SARS-CoV-2 and be tested in three to five days after their exposure. A “close contact” is defined as someone who spent a cumulative of 15 minutes within 6 feet of the person who tested positive during a 24-hour period. Anyone who has symptoms of COVID-19 should isolate themselves and get tested.

One reason we all need to wear masks indoors and in large outdoor gatherings is there are often delays in people being notified of having a “close contact.” To prevent additional spread of COVID-19, we can all mask indoors and in large outdoor gatherings proactively.

How do vaccinations and face coverings work together to combat the spread of the virus?

The COVID-19 vaccines are critical in our fight against SARS-CoV-2.  Our current COVID-19 vaccines are safe and highly effective at protecting people from severe disease and death from COVID-19. However, the vaccines are less effective at preventing mild or asymptomatic infection. Therefore, it is critical we continue to use multiple public health interventions to prevent the spread of the virus. These strategies include using face coverings/masks, physical distancing, increasing ventilation, disinfecting surfaces, washing hands, staying home when we’re sick, and other good public health practices. When we layer prevention strategies, we can reduce our risk of infection and the potential to spread disease.

If I’m vaccinated and get infected, it seems very likely that I’ll have no symptoms or some mild symptoms. All and all that doesn’t sound that bad, so why do I still need to be taking precautions like wearing a mask indoors and in crowded outdoor environments?

You should try to limit the spread of SARS-CoV-2 for both your health and safety and that of your friends, family, and community.

Viruses, like SARS-CoV-2, can change as they infect people. These changes can result in different “variants” of the virus. These variants can be unpredictable and could directly impact you (a vaccinated young person). It is possible a new variant could emerge that has high rates of death among young adults. During the 1918 influenza pandemic, there were very high death rates among young adults. Similarly, the 2009 H1N1 pandemic greatly impacted younger adults. Also, it is possible a variant could change in a way that causes our current vaccines to no longer protect us from severe disease and death. There is greater opportunity for the virus to change as it spreads more in the population.

In addition, the public health and scientific community is still learning about this virus. It is unclear what risk vaccinated people may have for developing “long COVID.” Long COVID is when someone has chronic long-lasting symptoms including fatigue, brain-fog, shortness of breath and other symptoms. Researchers are still working to understand this condition, but it can last weeks, months, and possibly longer. People who develop long COVID can have very mild or asymptomatic COVID-19 infections before developing this condition.

The more SARS-CoV-2 spreads the worse population health outcomes we observe including increased hospitalizations and deaths. Although you may think this does not impact you, some people are not able to receive care and treatment for other conditions, because of limited staffing and health care resources.

What indicators are you watching to determine when mask requirements might be eased?

There are several indicators to watch for when determining the public health strategies we need to prevent the spread of SARS-CoV-2.

First, we want to understand our setting/context. At Elon, we are in a high-density congregate setting, so we may need mask requirements longer than places that are not congregate settings. Second, we want to understand the level of community spread locally and across the United States. Third, we need to ensure the availability of vaccines to all people who want to be vaccinated. This includes children less than 12 years of age who cannot currently be vaccinated. Fourth, we should look to the guidance from our public health agencies. In some instances, it may be best to implement stricter measures than the current public health guidance, but we should ensure, at minimum, we are following the recommendations from our public health agencies.