In response to the rise of COVID-19 cases, the Philadelphia Department of Health and the Centers for Disease Control and Prevention are recommending that people resume wearing masks indoors in some areas as the coronavirus delta variant surges, even if vaccinated. Restaurants and bars around the country are taking it a step further, and have begun to ask patrons to provide proof of vaccination for indoor seating in the name of protecting their staffs and patrons.

The reaction has been polarizing and impassioned — the latest conflict between restaurants and customers since the start of the pandemic in March 2020. Those who favor the proof of vaccinations contend that private businesses are free to govern conduct, including mandating vaccines for workers. Critics counter that restaurants can have no stake in people’s medical decisions and argue that vaccinated people can still spread the virus, making these house rules ineffective.

The Instagram accounts of Cornerstone in Wayne and Martha in Kensington became battlegrounds over the weekend. Irwin’s, in South Philadelphia, did not allow comments on its post announcing the move.

Other restaurant operators have told The Inquirer that they were considering similar moves.

Many replied to Cornerstone’s post with messages of support. Others accused the restaurant of discrimination.

» READ MORE: Can my employer require me to get a COVID-19 vaccine?

Among the first to call for proof of vaccination in dining establishments was the San Francisco Bar Owner Alliance, a coalition of more than 500 bars. Then came Danny Meyer, the high-profile restaurateur who heads Union Square Hospitality Group in New York and Washington, who announced that all USHG employees must be fully vaccinated, effective Sept. 7. “If you really want to go unvaccinated, you can dine somewhere else, and you can also go work somewhere else,” Meyer told CNN. “I would call this a company policy rather than a mandate.”

The industry expressed optimism about a recovery in May 2021, but the recent spread of the coronavirus’ highly contagious delta variant has worried some restaurant workers and steered more patrons to dine outside. Meanwhile, this new turn is playing out as restaurant workers’ voices are increasingly being heard about all sorts of workplace issues, including safety.

“At Martha, we have been keeping an eye on the news and the variant,” said Olivia Caceres, who operates the popular bar with her husband, Daniel Miller. “I’m definitely the type of person who is going to read the energy of my staff, and my staff was increasingly uncomfortable” with working indoors among unvaccinated customers. “There’s no perfect map for us to figure out what to do,” she said. “We’re just trying to do what we can do to keep our staff and our neighbors safe.”

Martha began asking for proof at the door on Saturday, July 31. Those who could not produce a card or a photo of one were invited to dine outdoors. “We’re not turning anybody away,” Caceres said, describing the decision as one of Martha’s house rules, like not serving two alcoholic drinks at once. “Guests are coming in excited and ready to show cards. They’re totally all right sitting outside” if they don’t have one.

Michael Ferreri, chef and owner of Irwin’s, on the roof of the Bok building, said patrons are told the policy at the ground-floor reception area. Irwin’s will not allow those without proof to dine indoors or outdoors because the deck and restrooms are accessible through the dining room, said Ferreri, who said he implemented the policy for the safety of his staff, which is fully vaccinated.

“I want to be sure my staff is as safe and comfortable as possible,” Ferreri said. “I understand that people have their reasons behind getting vaccinated or not getting vaccinated. We see about 620 [customers] a week. It’s not a terribly safe environment.” As for the potential of losing business over his position, Ferreri said, “I think that putting human life over money is pretty important.”

Though many online commenters are complimentary and respectful, others are “pretty nasty about it,” said Caceres, at Martha, which posted its policy Saturday.

“Look, they’re entitled to their opinion,” Caceres said. “We’re not trying to change anybody’s minds. We’re just looking out for our neighborhood.” She said she turned off comments on the Instagram post when they turned into hate speech, so commenters took their comments to other posts.

Erin Elmore, a lawyer and commentator with the conservative Town Hall Media, reposted Martha’s announcement on her Instagram story and added the comments, “If you value freedom, spend your money elsewhere,” “This is un-American,” and “They turned off the comments — they are weak.” After Martha turned on comments, she accused the restaurant in a comment of “deleting all of the bad ones. I hope you go out of business! Expect a protest out front soon!”

Though Cornerstone announced the policy about six weeks ago in an email to customers, the bitter messages followed Thursday’s post. “We knew we would get pushback but not to the point of where we are right now,” said Christine Kondra, who owns the restaurant, market, and bottle shop with her husband, Nick. “I had to get the chief of police involved. We have had threats. We have been called Nazis. They have said we should change our name to Kim Jong Charcuterie. We have been told that we are breaking the HIPAA code.” (The federal privacy rule prohibits the unauthorized divulging of medical information but does not bar anyone from asking for information.)

“Somebody told me, ‘You could require people to wear a suit and tie to your restaurant, if you wanted to,’” Christine Kondra said. “At the end of the day, we’re not saying you can’t come to our restaurant if you’re not vaccinated. We’re saying this is just this one part of the restaurant” — the 20 indoor seats — that would require proof of vaccination.

“Some of the pushback that we got was, ‘What if it what if they have a fake vaccine card?’” Christine Kondra said. “And I was like, ‘Well, there’s only so much that I can control and I’m going to go on that.’”

Not all restaurateurs are in favor of the requests. Matt Lang, who operates Zig Zag BBQ next door to Martha (which is owned by the same group), cited a large virus outbreak among vaccinated people in Provincetown, Mass., for his decision to require masks for his three indoor picnic tables. “Not like people are breaking down the door to sit inside here anyway,” he said.