Philly’s music venues were supposed to get back to business as usual this week after nearly a year and a half of pandemic shutdowns.

The Met Philadelphia put on its first show Tuesday with violinist Lindsey Stirling. Ardmore Music Hall’s full-capacity shows begin Thursday with a Grateful Dead-themed “Jerry Week.” And Union Transfer reopens Friday with the first of five sold-out Japanese Breakfast dates. Dozens more shows are scheduled for indoor venues in the weeks ahead.

But the excitement is now tempered with alarm about the highly contagious delta variant — and confusion over the rules.

“The frustration is immense,” says Chris Perella of Ardmore Music Hall. “We should be in full celebration mode for our first full-cap shows in 17 months. Instead, we’re posting about COVID protocols … I’m stunned by how much things have shifted in one week.”

Fans are wondering: Will I have to prove I’m vaccinated — or show a negative test for the virus — to go see a band? Will masks be mandatory?

The answer is that it depends on the venue, and sometimes on which artist you’re paying to see.

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Union Transfer announced Monday that, at the band’s request, all attendees at the Japanese Breakfast shows will have to show proof of vaccination or proof of having tested negative for COVID-19 in the 48 hours prior to attending the show. Anyone who can’t will have their ticket refunded.

Sean Agnew, who co-owns and books the club, said that the policy only applies to the Japanese Breakfast shows, for now. There aren’t, as of yet, any plans to require proof of vaccination for the shows at the club next weekend — PVRIS on Aug. 13 and mewithoutYou on Aug. 14 and 15 — “though things are constantly changing,” he said.

The club has made mask wearing mandatory for all ticket holders at all shows, going beyond what’s required by the city.

Agnew was frustrated with the news conference on Tuesday in which Acting Health Commissioner Cheryl Bettigole only recommended that Philadelphia residents mask up indoors in public settings. “‘Strongly encouraging’ mask usage more or less means nothing,” he said. “So we’ll err on the side of caution this month and have our own mask policy in place.”

After its shows next weekend, UT will be closed for three weeks for a planned break and will reassess. Several tours have requested doing shows only for the vaccinated, Agnew said, “but a handful of artists have requested that we not check vaccination status. Concerts may be the next battlefield for this debate.”

Johnny Brenda’s in Fishtown, which just announced its reopening weekend with Birds of Maya on Sept. 3 and Electric Candlelight on Sept. 4, will also leave proof of vaccination and COVID-19 testing to individual artists’ discretion. The club’s masking policy hasn’t yet been determined.

City Winery, a chain that operates in eight cities, will require proof of vaccination or a negative test in all its locations. In Philadelphia, where neo-soul singer Dwele plays Friday, a poll of fans on the local mailing list found that 95% said they were vaccinated and were in favor of attending vaccinated-only shows, says owner Michael Dorf.

Dorf realizes he might lose business. “If they choose to not come because of the policy, that’s OK,” he says. “I’m OK with losing 10% of our business to stay alive. If we have to close again or if we have to go back to 25% occupancy, we’re going to be devastated.”

At Ardmore Music Hall, masks are now mandatory and “proof of vaccination or negative test will be at each artist’s discretion,” the club announced Tuesday. For this week, it’s not required for Splintered Sunlight on Thursday or Music of the Grateful Dead for Kids on Sunday, but is for Everyone’s Dead on Friday and Steve Kimock on Saturday.

The venue plans to continue with that model, and reaction has been “85% positive, loving and understanding,” Perella said, along with a fair share of “angry or hateful responses.”

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At South Jazz Kitchen, a mask mandate has been reinstituted in the venue when people are not eating and drinking. Ron Ozer, who books the Arden Gild Hall in Delaware, said starting with its opening show with Yo La Tengo on Sept. 22, proof of vaccination will be required.

And Hal Real of World Cafe Live said that although the venue doesn’t open until late September, “based on current data and circumstances, we will require vax proof or proof of a negative test.”

Industry observers across the U.S. don’t see another shutdown coming, “but there are going to be cancellations,” says Dave Brooks, who covers the concert industry for Billboard. “Outdoor shows should be OK, but some indoor shows will be canceled.”

Case in point: The Foo Fighters made headlines for playing a vaccinated-only show in June, but the band had to postpone a reopening show at the Forum in Los Angeles this month after a member of its entourage tested positive.

Bright Eyes opened its tour at Bethlehem SteelStacks with Lucy Dacus last week, but announced that while they are carrying on with outdoor shows on their summer tour, they’re postponing all indoor shows.

There are several sizable outdoor shows coming up on the Philadelphia concert calendar, including Hall & Oates’ Hoagie Nation at the Mann Center on Saturday and Phish on the Atlantic City beach Aug. 13-15.

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Those shows — and those at The Met in Philly and the BB&T Pavilion in Camden, as well as many other venues — are produced by dominant promoter Live Nation, which has not required proof of vaccination at its local shows. Patrons are being advised to check venues for masking requirements and recommendations. Masks are strongly encouraged for vaccinated patrons and required for non-vaccinated patrons at the Mann.

“We’re working closely with local officials and following the recommended safety guidelines,” a Live Nation spokesman said regarding shows at the Met. “We also encourage everyone who can to get vaccinated as that is the best way for us to take care of each other and get back to doing what we love.”

For Philadelphians, the crush of maskless people at Lollapalooza in Chicago sparked concern about the Made In America festival, which is scheduled to be back on the Ben Franklin Parkway on Labor Day weekend with Justin Bieber and Lil Baby headlining.

A spokesperson for Jay-Z’s management company Roc Nation said the festival, which draws as many as 50,000 people a day, “will follow all applicable CDC, state, and local public health guidelines in effect at the time of the festival.”