The co-chairs of the ABC Science Collaborative published an essay in The New York Times titled, “We Studied One Million Students. This Is What We Learned About Masking,” stating our position in favor of universal masking.

We have received a number of questions about ABC Science Collaborative research, and as co-chairs of the ABC, we are responding with this FAQ to answer many of those questions.

Does wearing a mask for 6-8 hours cause harm?

No. Those of us who work in healthcare wear masks all day, every day since April 2020. Masking is required at Duke University, Tufts University, Johns Hopkins University, and thousands of other hospitals, clinics, and health departments. Think about your own experience: If you went to the doctor anytime since April 2020, were you required to wear a mask? Was the experience harmful? Of note, universal masking is required for all physicians, nurses, support staff, patients (including children), families (including children), and visitors (including children).

In fact, 8 studies in 6 states have found that schools with universal masking policies had extremely low within-school transmission during the 2020-2021 school year (Learn more: Utah, Missouri, Georgia, North Carolina, North Carolina, North Carolina, Wisconsin, Virginia).

Does wearing a mask cause high levels of CO2?

No. Although a paper published earlier this year suggested that children wearing masks have increases in CO2, and this paper has been used by some to oppose masks, the paper was quickly retracted by the journal due to concerns about validity of the data.

Small, transient increases in CO2 occur in a number of circumstances, including exercise. Fortunately, the CO2 levels in our blood are very tightly regulated – any small increases trigger the body to breathe more quickly or more deeply. This can and does occur whether you are exercising or wearing a mask. Therefore, CO2 does not build up in blood.

Further, immunocompromised children and adults have long worn masks while in public, and it has been a common practice in some countries. None of these people develop high levels of CO2 in their blood; nor are they having trouble getting enough oxygen.

Does wearing a mask cause learning loss?

For children who are hard of hearing or have special needs, clear masks are available.

For the mainstream school setting, the learning loss from masking—and none has been documented to date—is trivial compared with the learning loss from getting sick from COVID-19 and missing school, from quarantining as a result of exposure at schools without universal masking, and from remote learning resulting from outbreaks in schools without masking (for example, Cobb County, Ga, Mooresville Graded School District in North Carolina, Johnston County, NC, Union Academy Charter School, and dozens of other districts had to shut down)—and for the 297 children admitted to the hospital every day for week of August 9-15, 2021.

Can wearing a mask alter facial development?

We have not seen this whatsoever in the past 18 months, and there are no reputable peer-reviewed reports of this.

The current goal of masking is to keep children and staff safe while awaiting FDA authorization of a safe and effective vaccine for children under 12 years of age and to achieve high rates of vaccination within the school-aged population. To assert that we will induce changes to bone structures of the face by wearing masks for the next few months is simply not true.

For decades, children who have had stem cell transplants and solid organ transplants have worn masks for months (and sometimes years) after transplantation without severe malformations to facial structure.

Can wearing a mask cause acne?

Acne can at times occur with masking. Fortunately, there are simple, available therapies for acne. In addition, acne does not result in death, while COVID-19 can.

Did ABC Science Collaborative use an unmasked control group for comparison in its research?

We acknowledge that we did not conduct a randomized trial (further comments below). In addition, we have acknowledged this in the public domain multiple times.

Does the lack of control group compromise the data on the effectiveness of masks in schools?

Prior to August 2021, we asked multiple districts that did not have universal masking to submit their data to Duke and to the ABC Science Collaborative. Not one district with voluntary masking was willing to submit data.

Our existing data are not perfect. However, the data from our study in the spring in North Carolina as well as the 7 peer-reviewed publications in U.S. schools from 6 states, from 6 different research teams investigating independently, studying more than 1,500,000 children and staff, and more than 100 school districts that support masking are the best data available and they are remarkably consistent. Those who advocate against masking have not produced a single peer-reviewed study of individuals in schools that demonstrates that masking does not work.

The only studies that have investigated individual risk of school-acquired infection using a combination of contact tracing (NC, NC, WI), testing (GA, MO), and whole genome sequencing (Utah) have consistently found limited transmission in the setting of masking regardless of the presence or absence of other mitigation measures.

What about schools that operate with voluntary mask policies?

Schools and districts that have tried to open with voluntary mask policies this summer and fall have not been successful. As of mid-August, 25 school districts that tried voluntary masking have reverted to universal masking. Most of the districts that made the masking policy change have done so in fewer than 10 business days. Sometimes the change has been because of infections and sometimes because of large numbers of quarantine.

Can the ABC Science Collaborative help my school district?

The ABC Science Collaborative has a free service whereby school districts can submit their data regardless of masking policy. Several school districts that do not require masking have stated their willingness to work with the ABC Science Collaborative this fall. We view this as a high-integrity decision on the part of these districts. While we respectfully disagree with their approach to masking, we are fully committed to supporting them and helping them be as successful as possible in providing a safe working and learning environment. Regardless of your position on masking (or vaccination, or any other policy), if your school district is willing to submit data, we would like to work with you. If you are interested, email abcsciencecollaborative@duke.edu.

The benefits to submitting data from your school district are:

• We will work with you to interpret your data free of charge.
• Your data will be confidential, and we won’t allow others to identify your data by name, nor will we identify others. We will allow you to compare your data in a confidential way to other districts of similar size and demographics.
• If you would like help in decision-making on when to add or subtract mitigation strategies, we provide support.
• Districts that submit data can engage in our twice-monthly peer-to-peer support calls where superintendents and assistant superintendents can bring forth concerns and solutions in a confidential setting, moderated by ABC Science faculty.
• We do not collect personal health information data. We do not collect any data that allows any individual to be identified.

Would a randomized trial be an effective way to get better data on masking? Would it be ethical?

Randomized trials are often considered the “gold standard” for research for good reason. By randomly assigning one large group of people one intervention and another large group a different intervention, placebo, or standard of care, researchers can see more clearly if the intervention is having a true effect. However, randomly assigning which children wear masks and which don’t during a pandemic is both unethical and impractical.

First, the overwhelming evidence tells us that not wearing a mask causes harm, so a trial asking people to not mask is unethical. Second, randomly assigning children to mask or not mask takes away a family’s choice to protect their child, which would limit how many families would want to participate in research. Low participation would make a randomized trial impractical because there would not be a large enough number of participants. The co-chairs of the ABC Science Collaborative have led multiple randomized trials, including trials for COVID-19, and understand the benefits and the challenges of this method. The choice to study the data without a randomized trial was clear.

Physicians practice medicine with a mask mandate in place for all staff, patients, and visitors in the healthcare environment. Such mandates follow research that is similar to the work in schools. There have been no randomized trials and no concurrent control groups in the healthcare setting. So, while healthcare workers are protected by mask mandates in their work environment, researchers would be asking hundreds of thousands of school staff and teachers to be subject to randomization without the same level of protection. Put another way, the researchers involved in a randomized trial would enjoy the protections provided by masking while randomizing school staff and school children to not masking with an endpoint of a potentially fatal infection.

How much time do researchers need to establish a randomized trial?

Even if we could ethically conduct a randomized trial, most randomized trials (even those related to COVID-19) are not completed and most that are completed take more than 36 months to write, secure funding, complete enrollment, and analyze data to find results.

Are there other studies that back up the findings from the ABC Science Collaborative?

The data from the spring of 2021 in North Carolina are not unique—they have been replicated in 7 other peer-reviewed publications with similar results (Utah, Missouri, Georgia, North Carolina, North Carolina, Wisconsin, California). Until other data are available and we have sufficient vaccination to protect children and adults in the school setting, universal masking is the appropriate policy.