This wasn’t supposed to be happening. For a moment, Steve Katsurinis was so surprised by what the state epidemiologist was saying that he couldn’t think at all.
As the chair of the Provincetown Board of Health, Katsurinis had helped to steer this little beachside town at the tip of Cape Cod safely through the last year and a half of the pandemic. It was his job to navigate the fast-evolving science and ever-changing federal and state guidelines, and until now, the town had fared well.
Just 65 people in the town of about 5,000 had tested positive there in all of 2020, in large part due to tight restrictions and a cooperative public. One homeowner described it as a “hamlet from the outside world.” And, just in time for the summer season, the community had achieved one of the highest vaccination rates in the state. Provincetown was open for business. Tens of thousands of unmasked people arrived each week to take part in the renaissance.
An entire month of the summer season passed without the peninsula’s sole health clinic recording a positive case. When an infected person appeared on July 6, officials hadn’t been too concerned. But then more and more people arrived in the waiting room in search of tests.
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And now, on a grim Zoom call at the end of the second week of July, the state was sharing a new statistic that would change everything, in Provincetown and across the country: Nearly three-quarters of the people who lived in or visited the town that month and tested positive for the new and virulent Delta variant of the virus were vaccinated.
Katsurinis did frantic calculations in his head. Everyone had known there would be breakthrough infections. But this outbreak seemed to be driven by vaccinated people. He found his voice.
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“So what happened here on the Fourth of July is going to happen all over America, at every holiday?” he asked the health and town officials on the call.
Nobody knew for sure. But suddenly, the dream of crushing COVID through vaccination seemed to be slipping away.
Within weeks, it was clear that whatever had happened among the partygoers of Provincetown had reshaped the scientific community’s understanding of the vaccines and shattered any illusions of a carefree post-pandemic summer for the inoculated.
“Recent outbreak investigations show that the Delta variant behaves uniquely differently,” said CDC Director Dr. Rochelle Walensky at a press conference July 27. “In areas with substantial and high transmission, CDC recommends fully vaccinated people wear masks.”
Privately, in an internal presentation that was leaked to The Washington Post, the federal agency was more blunt.
“The war has changed,” officials wrote.
There was little to fear in Provincetown as July approached. As a tight-knit community with experience battling the AIDS crisis decades back, the town had treated the novel coronavirus with collective caution from the outset.
The conservative strategy had paid off: Provincetown had no major outbreaks during the whole of the pandemic and only one death. When the state announced it would relax restrictions on masks and distancing at the end of May, officials discussed keeping local rules tight for a little longer, Katsurinis said. But they trusted the science, and the science said: Vaccinated people are safe.
“I’m an optimist. I think a lot of people are. I wanted to believe that we were doing the right thing. It was easy to believe that this was the right thing,” said Katsurinis. “When the experts tell you you can, you do.”
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Rob Anderson remembers in late June walking out the back door of the Canteen, the sweet little bar-on-the-beach seafood restaurant he co-owns, and seeing people in bathing suits eating — their feet in the sand, kids dancing to Motown music, dogs weaving between people’s legs, and the ocean wide and blue behind them. It felt like the old Canteen, the place he missed: crowded, easy, lively, and loud. People sharing plates of food and brushing up against strangers. “Is this OK?” he thought, reflexively. Then he remembered and he smiled: Yes, it was.
J.M. Jericho arrived from New York City with his husband on Saturday, July 3. It was cloudy and cool and wet but it didn’t matter. The couple thought of Provincetown as “our little town.” They loved its sense of community and quirky architecture, and were thrilled to see it hopping after the ghost town it had been when they visited the year before.
“There was this feeling of everybody breaking out of that COVID shutdown,” he said. “For a moment, we thought, ‘Oh, it’s just really over.’”
That weekend, hundreds of people lined up outside the Boatslip resort each afternoon at 4 p.m. for the Tea Dance, billed as “Provincetown’s biggest outdoor dance party.” Bouncers checked vaccination cards alongside IDs at the door. Rain that night washed out barbecues and outdoor parties, and some clubs and restaurants were still closed, so throngs of people squeezed into a handful of bars to dance the night away. The A-House nightclub was more packed and sweaty than anyone had seen in years. Some jokingly asked, “So COVID has been canceled?” But “a renewed sense of hope” filled the dance floor, according to one attendee.
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By Wednesday, Jericho couldn’t stop coughing. Both he and his husband had been vaccinated with the Pfizer vaccine back in April. On Thursday, he drove to Outer Cape Health Services to take a test.
His positive COVID result was only the fourth recorded at the clinic in 32 days. He fled the Cape immediately and sounded the alarm to his friends.
Town Manager Alex Morse heard about the first five or so cases that Friday, July 9. The town had anticipated a few positives, with thousands of people descending from San Francisco, Seattle, Miami, New York, and when Morse talked to the staff at the medical center, they told him the cases were all mild. No cause for alarm.
There was no discussion of canceling the legendary Bear Week, the annual celebration that caters to an older gay crowd, and on Saturday the rental houses emptied of the Fourth of July revelers and filled up anew.
But as Bear Week kicked into gear, talk of a growing number of positive tests began to swirl on social media.
A Bear Week discussion board online filled up with notes from vacationers who had returned home after the first week of July and taken to their beds. They were posting about coughs and headaches and fevers.
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“Is anybody else feeling sick?” one person asked.
Suddenly, the uninhibited joy of just a week earlier had vanished. Rob Anderson, the owner of the Canteen restaurant, walked into Outer Cape Health Services for a routine dermatology appointment and was startled to find the waiting room crammed with people, some of them draped over chairs. Even more unsettling was the quiet, the stiff way people held their bodies, and the suspicion that had returned to their eyes.
By the middle of Bear Week, positive cases were rolling in at 20, 30, almost 40 a day. By Thursday, Provincetown hit its peak positivity level of more than 15 percent, up from zero percent a few weeks earlier. Town health officials were meeting daily with the state, and samples were being sent to the Broad Institute in Cambridge for genomic analysis.
It was Friday or Saturday that Steve Katsurinis remembers sitting in that Zoom meeting, hearing how many of the positive cases were among vaccinated people, and realizing the full import of what was going on. He thought of the wastewater testing the county did to monitor virus levels, and how the levels had risen around Thanksgiving and Christmas of 2020.
Would COVID surge every time people gathered, he wondered, even if they were all vaccinated?
“We killed that Freddie Krueger, and here he is coming in the back door with Delta,” Katsurinis said. “You’re like, ‘Wait a second, you’re dead.’ ”
Four public health nurses were working around the clock and on weekends, trying to trace infections backward. But there was no single superspreader event; people seemed to have picked the virus up all over town. On Monday, July 19, Provincetown issued a mask advisory. On July 25, officials made the advisory a mandate.
Two days later, the CDC announced its turnabout on masks. Vaccinated Americans in areas of the country with substantial or high transmission rates should mask up, the agency said, citing the cluster in Provincetown.
“The more we learn about this virus and the Delta variation, the more we have to be worried and concerned,” said President Biden. “There’s only one thing we know for sure — if those other 100 million people got vaccinated, we’d be in a very different world.”
More than 1,000 cases have now been linked to the outbreak in Provincetown. More than 600 of those cases were diagnosed in Massachusetts, and a little more than 400 were confirmed out of state. California; Illinois; Connecticut; Washington, D.C.; Florida; Minnesota; Pennsylvania; Rhode Island; Washington; and New York all reported cases originating in Provincetown.
About 90 percent of all the cases involved the Delta variant, according to a CDC study, and almost three-quarters of people infected were vaccinated. Vaccinated patients had viral loads just as high as unvaccinated people.
“It’s really a reminder that when you’re vaccinated, you’re not invincible,” said Daniel Park, senior group leader of viral computational genomics at the Broad Institute, which is studying the Provincetown cases. Park’s team is trying to determine whether vaccinated people were indeed spreading the virus, as opposed to just becoming infected. The high vaccination rate in the cluster suggests that kind of “onward transmission,” he said, but his team hasn’t definitively proved it.
Still, vaccination remains the single best defense against the virus. J.M. Jericho got infected but his husband, cousin, and two friends they traveled with stayed healthy. About 110,000 people came and went in Provincetown across a two-week period — which means that about 109,000 people visited town but did not report contracting COVID.
Unlike outbreaks involving unvaccinated people, the vast majority of patients infected in Provincetown had mild to moderate symptoms. Only eight have been hospitalized, and none have died. This outbreak is nothing like the February 2020 Biogen outbreak in Boston, in which the virus tore through a completely unprotected population and sickened as many as 300,000 people all over the world.
Health officials have been emphatic: What we are learning about Delta suggests we are traversing new and unsettling ground but not that we are going back to where we were in the spring of last year.
By early August, the outbreak in Provincetown was under control. By Aug. 5, there were only 49 active cases in Provincetown residents. The town’s positivity rate was back down to around 3 percent and sinking.
“Vaccines have been a huge gift, and a huge scientific advance,” said Katsurinis. “Humans are resilient.”
Evan Allen can be reached at evan.allen@globe.com. Follow her on Twitter @evanmallen. Hanna Krueger can be reached at hanna.krueger@globe.com. Follow her on Twitter @hannaskrueger.