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Consensus Guidance on Face Coverings

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Updated May 6, 2021

While America’s health care workforce has played a critical role since the COVID-19 virus infected its first patient in the United States in early 2019, physicians and scientists alone can’t save American lives from being lost to COVID-19. We need a national, comprehensive, coordinated response to the pandemic, which the AAMC has previously described.

New guidance from the Centers for Disease Control and Prevention (CDC) released on April 27, 2021, suggests that, while the nation is in a period of transition, vaccinated individuals can now refrain from wearing masks in most outdoor settings unless in crowded settings such as concerts, sporting events, and other mass gatherings where not everyone may be vaccinated. Fully vaccinated individuals can also safely visit indoors with other fully vaccinated individuals without a mask.

Prior guidance for unvaccinated individuals remains unchanged except that even nonvaccinated people can exercise outdoors without a mask if they are alone or with members of the same household. They may also attend small outdoor gatherings without a mask if others are vaccinated.

Wearing a mask is one step everyone can take to protect themselves, their family, and their community in situations with elevated risk of infection. Clinicians and others working with patients wear masks and require all visitors to clinical sites to do the same regardless of their suspected COVID-19 status. A mask is not always comfortable and previously had not been a part of everyday life in the United States, but for the foreseeable future, the benefits outweigh the discomfort, particularly when indoors. While federal mask mandates have been issued in areas of appropriate jurisdiction, we are asking that state and local leaders — and all Americans — generally encourage the wearing of masks indoors and outdoors for those who remain unvaccinated. While vaccinations are safe and effective, they are not 100% effective in preventing infection.

Face coverings are critical for slowing the spread of the coronavirus, especially while many people remain unvaccinated. The medical community’s understanding of this novel virus has grown and evolved since March 2020, when efforts to slow the spread were first introduced. While we still have more to learn, our understanding of effective practices for prevention continues to grow. A study by the CDC followed up with 139 clients of coronavirus-positive hair stylists and found no symptomatic secondary cases; both parties had worn masks during the appointment.1 A study in Health Affairs examined the natural experiment of states’ mask mandates on community spread of COVID-19. The study estimates that, by late May 2020, between 230,000 and 450,000 potential COVID-19 cases were averted by the imposition of state mask mandates.2

Reinforcing the importance of prevention measures beyond monitoring symptoms and accelerating the distribution of vaccines, including wearing face coverings in many settings, is essential. Evidence shows that people unknowingly spread the coronavirus because they are asymptomatic, are not yet manifesting their symptoms, or have mild symptoms. One such study by the CDC found that of the 1,000 infected service members on the Navy ship USS Theodore Roosevelt, 1 in 5 had no symptoms and many had only mild symptoms.3 Wearing a face covering is one step most people can take to protect themselves, their loved ones, and the most vulnerable in their community.

The latest research demonstrates that well-fitting masks can help reduce the risk of virus transmission between individuals, allowing longer exposure while minimizing risk. Multilayer, well-fitting cloth masks; “double masking” 4; well-fitting N95s; and other masks such as KF94s can all reduce an individual’s exposure when everyone wears one. As knowledge grows about the virus and its methods of spread and transmission, these guidelines should be regularly reevaluated and updated.

List of Do’s and Don’ts


  • DO take a face mask with you wherever you go. Before you leave your home, check that you have your wallet, keys, phone, and mask.
  • DO cover your mouth and nose with a face mask to stop the spread of COVID-19.
  • DO wear a well-fitted face covering with no gaps around your nose and chin. If using a medical procedure mask, minimize any gaps by knotting the ear loops and tucking and flattening any extra mask material.5 
  • DO wear a mask with a nose wire.
  • DO wear a cloth mask with at least two layers (three layers when possible).
  • DO consider wearing a KF94, N95, or equivalent Food and Drug Administration (FDA) or NIOSH-approved mask in high-risk settings for maximum protection.
  • DO consider wearing a cloth mask over a medical procedure mask in high-risk settings if you don’t have a specialized high-quality mask like a KF94 or N95.
  • DO double-check any medical-grade mask purchases against the FDA’s list of approved masks.
  • DO wear a face mask indoors around people who are not members of your household unless you are fully vaccinated, in a small gathering, and limiting nonhousehold members to one household. (Everyone 2 years of age and older.)
  • DO wear a mask outdoors in public settings if you are not vaccinated when you expect to be around others — the safest option is to wear a mask, unless you are only briefly passing by others (e.g., running or walking by someone on the sidewalk). Fully vaccinated individuals can safely be outside without a mask except when at mass gatherings. (Everyone 2 years of age and older).
  • DO roll down the window of a car when sharing a ride or traveling with others who are not members of your household if you or others are unvaccinated.
  • DO wash your cloth face covering frequently.


  • DON’T forget to wear a face covering and stop the spread. Protect yourself and others.
  • DON’T leave your home without a face mask.
  • DON’T touch the front of your mask.
  • DON’T wear the face covering under your nose.
  • DON’T share your mask with others.
  • DON’T combine two disposable masks.

Consensus Guidance on Face Coverings

In regions where community spread is significant and/or growing, wearing face coverings indoors should be mandatory. The following practices are recommended:

  • Well-fitted face coverings that minimize gaps around the nose and chin are important. Loosely folded face masks and bandana-style coverings are better than no coverings; however, they still allow for the smallest aerosolized respiratory droplets to be dispersed.6
  • Wear face coverings with at least two layers (three layers when possible). Additional protection can be provided by wearing high quality, well-fitting masks with multiple layers of fabric or by wearing two well-fitting masks. If two masks are worn, the mask worn closest to the face should be a disposable mask, and the outer mask should be a cloth face covering.5 In July 2020, a study found that a double-layer cloth face covering was significantly better at reducing the droplet spread caused by coughing and sneezing than a single-layer one.7 Further research, published in February 2021 by the CDC, found that wearing a cloth mask over a medical procedure mask — or in the case of a medical procedure mask, knotting the ears loops together where they attach to the mask and then tucking in and flattening the resulting extra mask material — increases overall mask efficiency.4


  • The CDC had recommended that “all people 2 years of age and older wear a cloth face covering in public settings and when around people who don’t live in your household, especially when other social distancing measures are difficult to maintain.”8 This guidance should be followed by the general public but may be relaxed when the individual is vaccinated and only exposed to other vaccinated individuals and/or members of one other household.
  • The use of face coverings is critically important indoors, as compared to outdoors. Superspreader events, in which an infected individual causes many subsequent infections, are likely to occur indoors.9
  • All businesses open to the public, no matter how limited, should insist all customers be masked while indoors.
  • Wear face coverings when indoors, even when 6 feet apart, if not with household members (unless everyone in the room is fully vaccinated or you are only in the room with members of one other household). Some studies suggest that smaller droplets, known as aerosols, can remain in the air longer, though how long is not yet known.10


  • The “CDC recommends all unvaccinated people 2 years of age and older wear a cloth face covering in public settings and when around people who don’t live in your household, especially when other social distancing measures are difficult to maintain.”8 The safest option is to wear a face covering except for brief moments of exposure under 3 to 6 feet, such as when walking by someone on the sidewalk.
  • Face coverings are unnecessary outside in non-enclosed spaces if an individual does not reasonably expect to come within 6 feet of others.

State and local officials should support the distribution of masks for people experiencing homelessness, people who are incarcerated, and other vulnerable populations.

As the level of COVID-19 community spread reaches sufficiently low levels, face coverings may become optional. “Low levels” can be defined as low regional spread, no national hot spots that could seed the local ecosystem, and adequate contact tracing so all contacts of infected individuals can be identified and quarantined.

Face coverings do not fully prevent the spread of infection. As a result, widespread mask use does not diminish the importance of frequent hand-washing or replace social distancing practices, such as avoiding large gatherings. Nonessential activities and gatherings that bring people in the same room closer than within 6 feet of each other for more than a fleeting amount of time or that cause a more forceful exhalation, such as playing sports or singing, should continue to be avoided with or without face coverings when possible.

If all Americans work together, we can protect our communities and continue reopening our schools and economy. Please join health care leaders in encouraging your family, friends, and community to get vaccinated and — until then — to at least wear a well-fitted face covering every time they come within 6 feet of someone outside their household. The quicker we make face coverings our “new normal,” the faster we can overcome COVID-19.



The AAMC Research and Action Institute appreciates the expertise of the following individuals in developing this guidance:
Atul Grover, MD, PhD, executive director, AAMC Research and Action Institute
Ross McKinney Jr., MD, chief scientific officer, AAMC
Sheila Burke, MPA, RN, FAAN, adjunct lecturer in public policy, Harvard Kennedy School
Ashish Jha, MD, MPH, K.T. Li professor of global health; director, Harvard Global Health Institute
Megan Ranney, MD, MPH, associate professor of emergency medicine; assistant dean of Brown Institute for Translational Sciences; director of the Brown-Lifespan Center for Digital Health; associate professor of health services, policy and practice

The AAMC also thanks the following individuals for helping to develop this document:
Laura Pincus, MHA, manager, strategy and planning, AAMC Research and Action Institute
Amanda Field, PhD, former senior science policy specialist, AAMC


  1. Hendrix MJ, Walde C, Findley K, Trotman R. Absence of apparent transmission of SARS-CoV-2 from two stylists after exposure at a hair salon with a universal face covering policy — Springfield, Missouri, May 2020. MMWR Morb Mortal Wkly Rep. 2020;69:930-932. doi:10.15585/mmwr.mm6928e2.
  2. Lyu W, Wehby G. Community use of face masks and COVID-19: evidence from a natural experiments of state mandates in the US [published online ahead of print June 16, 2020]. Health Aff. doi:10.1377/hlthaff.2020.00818.
  3. Payne DC, Smith-Jeffcoat SE, Nowak G, et al. SARS-CoV-2 infections and serologic responses from a sample of U.S. Navy service members — USS Theodore Roosevelt, April 2020. MMWR Morb Mortal Wkly Rep. 2020;69:714-721. doi:10.15585/mmwr.mm6923e4.
  4. Brooks JT, Beezhold DH, Noti JD, et al. Maximizing Fit for Cloth and Medical Procedure Masks to Improve Performance and Reduce SARS-CoV-2 Transmission and Exposure, 2021. MMWR Morb Mortal Wkly Rep. 2021;70:254–257. doi:10.15585/mmwr.mm7007e1.
  5. Centers for Disease Control and Prevention. Improve How Your Mask Protects You. Updated Feb. 13, 2021. Accessed March 2, 2021. https://www.cdc.gov/coronavirus/2019-ncov/your-health/effective-masks.html.
  6. Verma S, Dhanak M, Frankenfield J. Visualizing the effectiveness of face masks in obstructing respiratory jets. Phys Fluids. 2020;32,061708. doi:10.1063/5.0016018.
  7. Bahl P, Bhattacharjee S, de Silva C, Chughtai AA, Doolan C, MacIntyre CR. Face coverings and mask to minimise droplet dispersion and aerosolisation: a video case study [published ahead of print July 24, 2020]. Thorax. doi: 10.1136/thoraxjnl-2020-215748.
  8. Centers for Disease Control and Prevention. Considerations for wearing masks. Updated July 16, 2020. Accessed July 31, 2020. https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-sick/cloth-face-cover-guidance.html.
  9. Hamner L, Dubbel P, Capron I, et al. High SARS-CoV-2 attack rate following exposure at a choir practice — Skagit County, Washington, March 2020. MMWR Morb Mortal Wkly Rep. 2020;69:606-610. doi: 10.15585/mmwr.mm6919e6.
  10. Prather KA, Wang CC, Schooley RT. Reducing transmission of SARS-CoV-2. Science. 2020;368(6498):1422-1424. doi: 10.1126/science.abc6197.

This is a publication of the AAMC (Association of American Medical Colleges). The AAMC serves and leads the academic medicine community to improve the health of all. The AAMC Research and Action Institute is a “think and do” tank that builds upon a long-standing AAMC strength of conducting and disseminating cogent research and analyses and informing and transforming practice and policy in U.S. health care. Learn more at aamc.org.

© 2020 Association of American Medical Colleges. May be reproduced and distributed with attribution for educational or noncommercial purposes only.