To mask or not to mask? With vaccines and new guidelines, the mask-faithful navigate a ‘weird gray area.’

When David Díaz went for a recent 5-mile run in Iowa City, he took along a partner he has depended on for more than a year: his face mask.

Díaz, 29, knew he did not have to. He’s fully vaccinated, and recent federal guidance says unmasked, outdoor ex ercise is safe. At first, he wore the mask around his neck. But after passing people one block later, he pulled it up - and then began wondering why. Was he posturing? Was he showing concern for others? Was he worried passersby would view him as an anti-masker? Was he actually being anti-science?

“At what point are you doing more harm than good and letting fear or something rule your life?” Díaz, a data analytics consultant, said days later. “It’s still a thing I’m trying to work through.”

Some Americans never fully embraced face masks, those swaths of fabric that became one of the seminal flash points of the U.S. coronavirus pandemic. But for many across the nation who did, rising vaccination rates and shifting public health advice are forcing a recalibration of a relationship with an accessory that has served as a shield against a deadly pathogen, a security blanket during a crisis, and a symbol - of regard for the common good, liberal politics or belief in science.

Now, after months of advising Americans to wear masks and stay six feet from most others, the Centers for Disease Control and Prevention says vaccinated people can, among other things, gather unmasked indoors and that everyone can exercise outdoors with household members - and with faces bared to the world. Suddenly, in the spring of 2021, donning a mask for a solo stroll outside, where scientists have found scant evidence of transmission, has become the unscientific approach.

“If I know it doesn’t offer me additional protection, it’s okay to wear it anyway - it’s okay to have that kind of cognitive dissonance,” said Zoë McLaren, an associate professor at the University of Maryland at Baltimore County who studies policies to combat infectious diseases. “You want people to understand the actual risks, and then they can choose the level of precaution they want to take.”

McLaren said she thinks the latest CDC guidance, with its traffic-light colored rubric, is scientifically sound, if a bit dense. It’s been criticized by others, including “The Daily Show” host Trevor Noah, who slammed it for being “unreadable” and allowing vaccinated people to do only “two more things without a mask on.” Others complain it is too complicated and it requires people to know whether others are vaccinated.

James Clark, vice president of public safety at the Urban League of Metropolitan St. Louis, said people in the north St. Louis areas where he works initially resisted masks, then “got fashionable” with them. But now Clark worries people are misinterpreting the CDC guidance.

“I think [the CDC] should have been a lot more succinct in their messaging because I see people now walking into gas stations without a mask on, and the gas station cashier says, ‘You can’t come in without a mask,’ and then the person says, ‘Well, I thought we didn’t have to wear masks no more?’”

That confusion is common, said Faisal Khan, director of the St. Louis County Department of Public Health.

“People are so fixated on wanting to see their own individual situation represented or explained by those guidelines, and that’s never the purpose of the guidelines,” said Khan, who said his office receives a continual stream of calls and emails with “people screaming at us about why they cannot take their masks off” or questions about “which situation they should be masked in or not.”

At a macro level, mask-wearing in the United States has not been driven by public health advice or mandates, researchers and pollsters say. It is strongly associated with political affiliation. An Ipsos poll released this week found that 57% of Americans said they always wear masks when they leave the house, with Democrats more than twice as likely to do so than Republicans.

But there are signs of a new trend: The poll found that 63% of all vaccinated respondents always wear masks outside their homes, down from 74% in mid-April.

That is “a relatively significant shift,” said Chris Jackson, senior vice president and head of polling at Ipsos. “I do think that is somewhat attributable to CDC’s updated guidelines, and Democrats essentially having some sort of signal that yes, it is okay to change your behavior.”

At a micro level, however, this can feel like an awkward, in-between stage of coronavirus risk assessment. To wear or not to wear is not necessarily a simple question.

In State College, Pa., Nate Whitehill found himself taken aback on a recent evening when he saw a group of college students crossing a street unmasked. Then he had what he called an “epiphany,” remembering the CDC approved, if the students were vaccinated. And yet although he has had his Johnson & Johnson shot, Whitehill said he is figuring out the contours of vaccinated life. He recently went to his first pandemic-era dinner inside a restaurant, but he still wearing his mask outdoors.

“It’s hard to say when it’s going to hit that comfortable point that people can just be outdoors without a mask and not only not worry about covid, but also not have to worry about what the people around you are thinking,” said Whitehill, 31, who works at Pennsylvania State University. “It’s not like you’re going to run up to people and say, ‘I’m vaccinated.’”

Rob Hart, who’s been vaccinated since taking part in the J&J trial last fall, almost wanted to do that the other day. Hart, a novelist, said he still believes in the value of masking in public, in part to signal concern about others’ welfare. But as he emerged from a subway station in Manhattan, he took off his mask to get some fresh air. A man about 20 feet away - his own mask below his chin - promptly yelled at Hart for being uncovered.

“I was kind of speechless for a minute,” Hart said, adding: “This is such a weird gray area, because supposedly if you’re vaccinated and distanced, you don’t have to wear a mask. But how do we know if the people who aren’t wearing masks are vaccinated?”

On a cool but sunny afternoon this week, Roxana Henning, 46, watched as her 9-year-old son, Nathaniel, pumped his legs on a swing at an uncrowded park in the Chicago suburb of South Barrington. A few feet away, a sign warned that the playground was not sanitized and advised visitors to wear masks.

Henning, a part-time cardiovascular nurse who is vaccinated, did not wear one. But she said she planned to in a few days, when she expected to attend an in-person, outdoor church service for the first time in 14 months.

“I don’t have to protect myself, right?” she says. “But I want to protect other people.”

Nathaniel, on the other hand, donned a blue surgical mask.

“It just makes me feel comfortable and a bit safer,” the boy said. “The only time I ever enjoy taking it off is at home.”

Adding to the confusion in some places are local mask ordinances, which may differ from CDC guidance. In Massachusetts, Gov. Charlie Baker, a Republican, recently relaxed the state mask mandate for people outdoors and able to distance. But the Boston suburb of Brookline is keeping its town mandate for now.

At Tatte, a popular cafe on Brookline’s main drag, Beacon Street, Samantha Wong ate pastries with a friend at an outdoor table surrounded by chickadees searching for poppy seeds and crumbs. Wong, a 24-year-old portrait photographer who’s had her first vaccine dose, said she would continue to wear her mask outside even after receiving her second.

“I worry that people taking off their masks outside will lead to everyone not wearing one, and then will lead to people taking them off inside,” she said. “And I’m worried about the variants.” Asked when she might feel comfortable leaving it at home, Wong said: “Maybe fall 2022? Or maybe even spring 2022?”

Brookline resident Kathleen Vandenberg, 46, lives just 20 feet from the Boston border. She is planning to start running again next week - and when she does, she’ll do so in Boston. She has mild asthma, and breathing while running is easier without a mask. But she plans to keep it on her chin - not for anyone’s safety, but to avoid being seen as anti-mask.

Vandenberg, a senior lecturer in rhetoric at Boston University, knows that is a “symbolic and social” choice. But so, she said, is Brookline’s. The town has recorded fewer than 2,300 covid-19 cases since the start of the pandemic and has high vaccination rates.

“All along, we’ve been told to ‘follow the science.’ And the science says that the risk of transmission outside is low, especially if you’ve been vaccinated and keep your distance,” Vandenberg said. “The mask-wearing mandate here seems like it’s more about shame than science,” she said.

Jared Wilkins, lead pastor of Parkcrest Christian Church in Long Beach, Calif., is fairly sanguine about it all. He has started having more one-on-one coffees, outdoor lunches and front-porch visits with congregants. Often, these meetings involve a delicate conversation - about the other person’s vaccination status, whether to sit outside, whether to mask.

“There’s this weird balance that we’re in right now, when we haven’t reached herd immunity, and for people who are vaccinated, the risk is incredibly low,” Wilkins said. “For the next couple of months, it’s just going to be weird, so let’s lean into that weirdness.”

The default has been to mask, said Wilkins, 39, who’s partially vaccinated. But once he’s fully inoculated, he plans to “act vaccinated,” he said, by easing up on the mask - in part to encourage others to get their vaccines. “I’m not going to be reckless, but for us, it’s really important to follow our city and state guidelines and ask, ‘What are we modeling in this moment?’”

Sue McAvoy and Bill Tucker were not thinking much about modeling when they met the other morning for a walk on Atlanta’s BeltLine, a popular trail system built on former rail corridors. Friends since college, the two 65-year-olds, both vaccinated, were simply delighted to have their first in-person meetup since the fall of 2019.

Both said they remain cautious. McAvoy, a retired career adviser and self-described “super-hugger,” said she has taken the opportunity to meet - and hug - several close friends since getting vaccinated, but she still avoids most indoor spaces other than the grocery store.

Tucker, a retired investment banker, misses visiting his local LA Fitness four times a week, as he did regularly before the pandemic. He doesn’t feel safe there, he said. “I do hope that the numbers improve enough that this all ends real soon,” he said.

But on this day, under cloudy spring skies, the old friends were at least together again. And neither wore a mask.

The Washington Post’s Eric Berger in St. Louis; Erin Chan Ding in South Barrington, Ill.; Alex Kellogg in Atlanta; and Joelle Renstrom in Brookline, Mass. contributed to this report.