Why Not Just Tell Everyone to Wear Masks?

An internal presentation circulated within the Centers for Disease Control and Prevention last month, and eventually obtained by news organizations, offered clear advice for countering the contagious Delta variant: “Given higher transmissibility and current vaccine coverage, universal masking is essential.”

But the recommendation issued by the agency was considerably more nuanced, advising Americans, vaccinated or not, to wear masks in indoor public settings in areas with “substantial” or “high” virus transmission.

At the time, that included at least 80 percent of Americans. As infection rates soar, some experts are now wondering: Would it have made more sense just to call for everyone to mask up?

“Given the rising rates across the country, the clearer message would be, ‘In all parts of the country, wear a mask in public indoor settings,’” said David Michaels, professor of environmental and occupational health at the Milken Institute of Public Health at George Washington University.

In addition to Americans in Covid-19 hot spots, C.D.C. officials also recommended universal indoor masking for teachers, staff, students and visitors to schools, regardless of where they are and regardless of individual vaccination status.

And the agency suggested that people “might choose to mask regardless of the level of transmission” if they or someone in their household were immunocompromised or at increased risk for severe disease — or unvaccinated, a category that includes all children under age 12, who do not qualify for immunization.

Also on the list: people who are overweight, smoke or have a disability, and anyone who has been in close contact with someone with confirmed or suspected Covid-19. That’s a lot of Americans.

“The messaging from the C.D.C. was less than optimal,” said Dr. Ezekiel Emanuel, vice president for global initiatives at the University of Pennsylvania. “We need to be clear and relatively simple about it.”

Advice on masking from federal health officials has been changing throughout the pandemic. In February 2020, Americans were urged not to buy masks, which were in short supply. In April 2020, officials recommended that masks should be worn outside the home. In May of this year, the C.D.C. said vaccinated people no longer needed to wear masks.

Agency officials did not respond to requests for comment about the latest revised recommendations. But the agency’s director, Dr. Rochelle Walensky, has said she was compelled by early data indicating that the Delta variant had changed the equation and that vaccinated individuals could spread the virus on the rare occasions when they were affected.

A significant piece of evidence emerged from an outbreak in Provincetown, Mass., over the Fourth of July weekend. Nearly a thousand people were infected, the majority of whom were fully vaccinated.

But many Americans have no idea week to week whether they live in a community with substantial or high transmission of the virus.

The definitions aren’t easy to grasp: Substantial or high transmission means any community where there are at least 50 new infections per 100,000 residents over the previous seven days, or at least 8 percent of tests are positive for infection over that period. (The agency maintains a map.)

A simpler mask recommendation probably wouldn’t have smoothed the way for mandates in a state like Texas, where two state judges this week allowed officials in Dallas County and Bexar County, which includes San Antonio, to begin imposing mask requirements despite an executive order banning them by Gov. Greg Abbott.

In many communities, mandates are gaining traction, and already the nuances about transmission rates and underlying conditions have been left aside. It’s easy to see why: As of Tuesday, the virus was spreading rapidly in 90 percent of U.S. counties. And masking is swiftly effective.

Masks “are actually amazing, because they work immediately — they start reducing transmission today,” said Julia Raifman, an assistant professor at Boston University’s School of Public Health. “Every case they prevent prevents several other cases, so their effectiveness grows over time.”

Wearing a mask also helps protect children who can’t be vaccinated yet, and others who are susceptible, like the elderly and those with compromised immune systems, who may not be able to mount a vigorous immune response following vaccination.

Masking also helps to prevent the virus from circulating, reducing the chances that it will mutate, possibly into a form more virulent that may evade vaccines altogether.

“If you allow the virus to freely circulate and not try and stop it, sooner or later there is a likelihood that you will get another variant that could, I’m not saying it will, but could be more problematic than the Delta,” Dr. Anthony Fauci, the nation’s top infectious disease expert, said Sunday on NBC’s “Meet the Press.”

The C.D.C. noted that Black, Hispanic and Native Americans are at higher risk of Covid-19, but said nothing further about minority communities adopting masking measures.

A universal masking recommendation might have helped protect vulnerable communities, including communities of color, where vaccination rates have lagged partly because of mistrust of the medical system and partly because of persistent problems with access to health care, said Dr. Rhea Boyd, a pediatrician who studies the relationship between structural racism and health.

“If you live in a neighborhood where a lot of people are not vaccinated, you are being exposed to the virus a lot,” Dr. Boyd said.

Still, some experts are sympathetic to the fine line that the C.D.C. must tread when issuing changing advice — especially on masking, which has become a cultural and political flash point.

Mask mandates can threaten the livelihoods of restaurants, bars and other indoor venues that serve food. In Louisiana, Gov. John Bel Edwards temporarily reinstated a statewide indoor mask mandate earlier this month amid a surge in cases. But he made an exception for “anyone who is consuming a drink or food.”

By setting localized benchmarks, the agency’s mask recommendation “gives everyone something to look forward to,” said Dr. Carlos del Rio, an infectious disease specialist at the Emory University School of Medicine in Atlanta. “At the end of the day, the C.D.C. is a science agency that responds to politicians.”

Still, he added: “If you’re indoors, you should wear a mask.”