America’s split with masks turned out to be a brief hiatus. After getting their shots in the spring and early summer, many people figured they could dump their face coverings for good—a sentiment the CDC crystallized in May, when the agency gave fully immunized people its blessing to largely dispense with masking, indoors and out. Yesterday, the agency pivoted back, recommending that even fully vaccinated people wear masks under certain high-risk circumstances, including in public indoor spaces in parts of the country where the virus is surging, Director Rochelle Walensky said in a press briefing. (She specified places where new case numbers exceed 50 per 100,000 people in the past seven days; that currently includes about two-thirds of U.S. counties.) With an ultra-contagious SARS-CoV-2 variant rampaging, face coverings are being called upon to once again supplement the protection offered by vaccines.
The CDC’s decision, which many public-health researchers have been anticipating for weeks, might look like a flip-flop or a fumble, some sort of masking mea culpa. But to me, and the experts I talked with, redonning masks (or simply keeping them on, as many people have) is not some shameful regression to the dark ages of the pre-vaccination era. Nor is it an indictment of the COVID-19 vaccines, which are doing an extraordinary job of curtailing the global burden of disease. Instead, it’s a doubling down on two defenses that we know work, and work well together.
Like any dynamic duo, masks and vaccines share a goal—preventing infection, disease, and virus transmission—and they accomplish it in complementary ways. “They should be seen hand in hand, as helping one another,” Abraar Karan, an infectious-disease physician at Stanford University, told me. We now understand this notion better than ever before, and many experts think anyone who wants to reduce their risk of catching and passing the virus should use both, CDC criteria notwithstanding.
Masks, after all, are reemerging in response to the fast-changing conditions around us—offering another layer of protection at a time when we need it most, in much the same way we seek out umbrellas when it rains, sunscreen when it’s sunny, and better security systems when our neighborhood crime rates tick up. “With Delta being such a dominant force, we need to include every layer we can think of,” Akiko Iwasaki, an immunologist at Yale University, told me. The vaccines are excellent. But while so many people remain vulnerable, and the virus continues to shape-shift, shots can’t shoulder the burden of protection alone. Our understanding of masks is evolving; for now, they still have a crucial role to play, as a partner to the shots we’ll be depending on long term.
Partnering masks and vaccines is, in many ways, a natural move. If an unmasked, unvaccinated body is like an unprotected bank, vulnerable to burglars, these two tools are akin to the different high-security measures used to prevent a heist. Shots steel the institution from the inside out, papering its walls with most-wanted posters and alerting bank personnel to upswings in local crime. Supersensitive alarms get installed at windows; extra security guards are stationed throughout the building; the local sheriff’s office is put on speed dial. Should thieves try to force their way in, they’ll be recognized as familiar foes and get arrested on the spot, maybe before any real damage can be done.
COVID-19 vaccines have proved themselves ace at deploying these safeguards and preventing symptomatic disease, especially in its most severe forms, even when tangoing with variants. That is the classic vaccination modus operandi: fortifying our defenses so a pathogen has higher hurdles to clear.
But even vaccinated immune systems can be somewhat foiled when local conditions change. A well-armored bank will still be better off than an unsecured one, but could struggle to thwart career criminals—ones who are savvy enough to show up en masse, move fast, and use brutal tactics. And more of those robbers might make it out of the scuffle unscathed and eager to hit up a neighboring bank. Vaccine-prepped immune systems are still mostly clobbering Delta, the SARS-CoV-2 variant that’s now found in 80 percent of the virus samples being sequenced across the nation: People who have gotten all their shots are a lot less likely to experience symptoms, hospitalization, or death, and don’t seem to be responsible for much virus transmission. But Delta also appears to be especially good at accumulating in airways, and seems to eke past some of our immune defenses. These troubling traits might make it easier for the virus to mildly sicken some inoculated individuals, and perhaps spread from them as well. Vaccines are an imperfect shield; variants like Delta find their way through the cracks.
Masks cut down on all of this risk. If vaccines shore up security from the inside, face coverings (which, you know, literally cover your face) erect a sturdy blockade around the bank’s exterior—fences, bars, better locks, and ID checks at an intruder’s typical point of entry. Masks are physical barriers; they’re “great at preventing exposure to large doses of virus” before the invaders even enter the premises, Iwasaki said. And in the same way that it’s easier for security guards to incapacitate just a few crooks busting through the door, “the less virus you need to fight off, the better—I think that’s pretty clear,” Marion Pepper, an immunologist at the University of Washington, told me. Masks, in other words, curb the amount of labor our immune systems are forced to do—in some cases, maybe eliminating the threat entirely. In that way, they accomplish something vaccines can’t: Unlike immune cells, they don’t have to wait until after the virus has broken into the body to act. That’s an especially big asset for people whose bodies are less equipped to respond to vaccines, including the elderly and the immunocompromised, populations the CDC says should mask more vigilantly indoors, regardless of where they live.
Masks might be a particularly important pairing for our current vaccines, which are administered in an arm muscle, rather than the nose—SARS-CoV-2’s natural point of entry. The shot’s contents will still effectively school immune cells and molecules all over the body, but they won’t do much to marshal defenders that specialize in guarding the slimy tissues carpeting the airway and gastrointestinal tract. It’s the difference between keeping security guards on retainer in a bank’s back room, and posting agents at the building’s entrance: Defenses will be mounted either way, but fighters who have to scramble from one location to another will probably lose speed and oomph. A barrier that waylays some viral particles, however, might buy these guards time to rush to the fore. Masks reduce the strain on the body, and keep immune cells in a zone where they can comfortably fight.
Our vaccines are very powerful, but their performance was first measured in clinical trials while masking was widespread. Study volunteers were “asked to act as if they were unvaccinated, and keep all other protections in place,” Michal Tal, an immunologist at Stanford, told me. The startlingly low rates of illness among vaccinated volunteers in those studies likely aren’t attributable to the jabs alone. Even against an earlier iteration of the virus, the shots were being supported by an entourage of precautions; mirroring that initial tag-team approach might not be a bad idea.
The combo of masks and vaccines does a number on outbound viruses as well. Unimmunized, unmasked bodies are good stages for pathogens to reproduce unfettered, then hop into a nearby human. Vaccines coach immune cells to vanquish as many viral particles as they can; masks trap any potential escapees inside. “People need to remember we live in very interconnected societies,” Karan said. While vaccinated people might remain mostly safe from serious disease, plenty of the people around them—especially those who remain uninoculated, including young kids—remain at much higher risk. A virus that keeps spreading, even silently, makes the pandemic that much harder to end.
Karan points out that masks are also a great insurance policy. Vaccines still carry uncertainties: Although experts think that COVID-19 shots are reducing all forms of infection and disease, the extent to which they block long COVID remains murky. Researchers also don’t know when vaccine-trained immune cells might start to forget the coronavirus, or when the pathogen might mutate into more evasive forms. If we end up needing boosters or reformulated vaccines, face coverings might keep some people from falling sick while those reinforcements arrive. “I think masks are our lowest hanging fruit to buy us time,” Karan said.
Some people are already criticizing the CDC’s announcement as a baffling U-turn, maybe even a bellwether of worse restrictions to come. Experts told me that’s the wrong way to view the update, which should be considered an improvement over the status quo—a step forward, not a step back. Combining masks and vaccines reaffirms that we know how to protect ourselves against this fast-changing virus, and match the curveballs it throws our way. Taison Bell, a critical-care and infectious-disease physician at UVA Health in Virginia, told me he sees masks as empowering—not some handicap he’s been saddled with. “It doesn’t represent something that restricts my freedom,” he said. “It allows me to enter a space and do what I need to do.”
The shift in guidance is, in a way, crystallizing a new attitude toward masking, one that will probably stick around in some form or another, even after the pandemic comes to an official close. These past 16 months have underscored the power of masks to prevent all manner of pathogens, and stave off some medical conditions; face coverings might become standard practice, socially, seasonally, as people get more in tune with public health. That’s the upside of crisis. It forces us to react, and hopefully react well. It calls on us to adapt, when we realize our circumstances have changed.