It was a battle to get their insurance to cover Idan’s infusions, Akiva said; ultimately, they were able to get coverage for the treatment he would receive at home, but not the infusions in the hospital. And when the family chose a hospital to do Idan’s bone-marrow transplant after months of research, they faced another fight. The hospital in Seattle—across the country from their home in Manhattan—used treosulfan, a drug that didn’t have as many side effects but was still in clinical trials in the U.S. Eventually, he said, the family’s insurance company agreed to part of cover the procedure, but they were still overwhelmed by the amount they owed beyond what insurance would pay for—and knew that more bills were coming.

So they turned to the Internet.

In May, a month after Idan’s diagnosis, Amanda and Akiva launched a page on YouCaring.com, which describes itself as a fundraising website for “personal and charitable causes.”

“We need your help raising funds to enable us to make sure that, no matter what happens to us, Idan has the best possible medical care, a successful transplant, and enough funds to cover the medical costs he will incur along the way,” they wrote. “We know we cannot do this alone.” Their goal was $250,000.

Within the first two weeks or so, Akiva said, “we raised almost $50,000 or $60,000, just from family and friends.”

Then, in July, The New York Daily News published a story on the Zablockis’ fundraiser; over the course of the next week, CBS, ABC, and NBC all ran stories on the family’s struggle to pay for Idan’s treatment. The money began pouring in even faster.

“At that point, there were a lot of people donating that we didn’t know who they were,” Akiva said. The media attention “was a huge bump as far as the legitimacy, because there are so many medical fundraisers out there.”

Which sometimes made him and Amanda wonder: Why had Idan’s been the one to catch on? “We were always trying to figure that one out,” he said. “Over those few weeks when there was the most attention, we were like, ‘Why is everybody so interested?’”

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Sites like YouCaring, GoFundMe, and Indiegogo Life cumulatively host thousands of pages set up by people looking for help with medical expenses, from cancer treatment to in-vitro fertilization (IVF). These crowdfunding pages are a place for family and friends to help out and receive updates on the status of a loved one’s health—but they’re also a place where strangers can log on and make a donation to someone they’ve never met before.

“I think we’re seeing the emergence of what we sometimes call peer-to-peer charitable giving,” said Leonard Lee, the head of communications for YouCaring. “So the notion that you’re not just giving to an organization that then decides how it’s going to use the funds. [Donors] can say, ‘I’m giving to this specific person, I identify with their need.’”