ARI SHAPIRO, HOST:
Last week the CDC changed its guidance and said, yes, fully vaccinated people do still need to wear masks indoors. The reasoning had to do with a large cluster of cases that started over Fourth of July weekend in Provincetown, Mass. By public health standards, the turnaround time from the outbreak to the CDC analysis to action was lightning fast. NPR's Selena Simmons-Duffin has the exclusive story of a citizen scientist who helped give the CDC a head start in their investigation. Hi, Selena.
SELENA SIMMONS-DUFFIN, BYLINE: Hi, Ari.
SHAPIRO: You and I have both been to Provincetown. But for the uninitiated, let's just explain. It's at the tip of Cape Cod, historically an artist's colony. And every summer, many gay men from all over the country flock there for vacation. What happened this year?
SIMMONS-DUFFIN: So this year there was extra excitement. Of course, because the pandemic had kept friends apart, there was no dancing, no gathering. A lot of people came feeling really joyful and safe because they were fully vaccinated. And this year it was also raining the weekend of July 4, which meant all of these people from all over the country were indoors even more than usual. This is how Cameron Thomas of Chicago described his first night out in P-town.
CAMERON THOMAS: It was one of the most, like, packed dance floors I've probably ever been on - like, shoulder to shoulder, wall to wall, front to the back of the club.
SIMMONS-DUFFIN: By midweek, people started to get a sense that something was up. Zorik Pesochinsky remembers two of his housemates were coughing. And he said to them...
ZORIK PESOCHINSKY: So at what point are we going to acknowledge that this is probably COVID? And they pushed back. They were like, no, it's not. Like, we're vaccinated. We're not even getting that sick. This is just a cold.
SIMMONS-DUFFIN: Later in the week is when the positive tests started to come in. Sean Holihan had just traveled back to Washington, D.C., and he heard that someone he'd been with there had just tested positive.
SEAN HOLIHAN: So that made me realize that I should get tested as well.
SIMMONS-DUFFIN: Ari, all three of the people you just heard from - all were fully vaccinated. All tested positive that weekend after being in Provincetown.
SHAPIRO: So texts and emails are flying among these people who, upon getting home from Provincetown, realized that they contracted COVID despite the vaccine. How did the CDC get involved?
SIMMONS-DUFFIN: So this is the part of the story where Michael Donnelly comes in. He is a data scientist in the tech sector by day. He got involved in COVID data tracking last year and launched a forecasting website called covidoutlook.info. So he knows COVID data, and he knows statistics. And when Donnelly started to hear about lots of people - whole houses full of people with breakthrough infections, it just seemed odd to him.
MICHAEL DONNELLY: That full allotment of people that I know that I would expect over the course of this year to get a breakthrough infection were getting a breakthrough infection in a single week.
SIMMONS-DUFFIN: So over the next few days, he started reaching out to friends like Zorik and Sean and Cameron to find out, were you there, and are you sick, too? And he ran what he was finding by his covidoutlook research partner, an epidemiologist at Drexel University named Michael LeVasseur, who agreed it seemed concerning. Donnelly ended up pulling together a spreadsheet of over 50 cases with their COVID test results, symptoms, vaccine status, home city and more. At that point, he decided he needed to get public health officials involved.
SHAPIRO: And how do you do that? It's not like there's a number for the CDC where you can just say, I've got all this data; let me hand it over to you, right?
SIMMONS-DUFFIN: So as it happened, Donnelly actually had a contact at CDC. His name is Dr. Demetre Daskalakis. He normally heads the agency's HIV prevention efforts, but right now he is detailed to the agency's COVID response. Before that, he worked in the New York City Health Department. And that's how these two know each other - from the early days of the coronavirus pandemic in New York City. So Donnelly reaches out to Daskalakis about this spreadsheet, and he says, send it over. Here's Daskalakis.
DEMETRE DASKALAKIS: It's quite certain that if we didn't have the heads-up from Michael because of what he was seeing among his friends and, you know, with his statistician hat on, we wouldn't have heard about it as rapidly, and it wouldn't have been as rapturous as an initiation of an investigation of response as we had.
SHAPIRO: And that's what led to the report last week that prompted the CDC to change its mask guidance for the entire country.
SIMMONS-DUFFIN: Exactly. This information was a big part of that change. Now, Donnelly is quick to say he did not do the investigative work here. The public health professionals did, and they were able to learn a lot. They found that nearly three quarters of the cases identified were breakthrough cases, that the delta variant was the culprit and, most surprisingly, that in a sampling of vaccinated and unvaccinated people, the amount of virus was nearly identical. And that is what signaled vaccinated people probably could spread the virus to each other, and new precautions were needed to protect people.
SHAPIRO: You know, in these stories from Provincetown started to trickle out last week, I tweeted, leave it to the gays. This ain't our first pandemic. Now that you've reported out how this all happened, how much do you think it does reflect lessons that gay men learned during the AIDS crisis?
SIMMONS-DUFFIN: Absolutely. I think this is a huge part of the story. The community has had practice with the HIV pandemic, and that's something that Daskalakis has been thinking about, too.
DASKALAKIS: It's, like, a community that believes in science and public health, like, stepping up to the plate. I have to say that out loud because literally I get goose bumps thinking about it.
SIMMONS-DUFFIN: Donnelly told me he thinks it's no accident that this community contributed so much to CDC's understanding of the coronavirus. And he hopes the new guidance that came out of that understanding has helped keep more people safe.
SHAPIRO: NPR's Selena Simmons-Duffin, thank you.
SIMMONS-DUFFIN: Thank you. Transcript provided by NPR, Copyright NPR.
