In a photo from 2009, Bill Halford, who was then 40 years old, looks like a schoolboy who hasn’t quite grown into his big ears. He wears an ill-fitting red shirt tucked into belted khakis; his jawline is square and his eyes are full of wonder. The picture was taken at Southern Illinois University, where he was a respected professor. A few years before, he had made a significant discovery—one that would determine the course of his life.

Halford, a microbiologist, had taken an interest in the peculiar nature of herpes—how it lies dormant in the nervous system and reactivates to cause disease. Herpes is one of the most pervasive viral infections in the world, sometimes causing painful genital blisters, and it has frustrated scientists attempting to find a cure. But in 2007, Halford realized that a weakened form of the virus he’d been studying might serve as a vaccine. He designed an experiment in which he inoculated mice with this variant, then exposed them to the wild-type form of the virus. In 2011 he published the results: Virtually all the mice survived. By contrast, animals that were not injected with his vaccine died in large numbers. It was promising science.

That same year, however, Halford became seriously ill. At first he thought he had a sinus infection, but it turned out to be a rare and aggressive form of cancer, sinonasal undifferentiated carcinoma. Halford was 42 years old at the time, with two teenage children. He underwent chemotherapy and radiation followed by surgery, but he was told that the form of cancer he had did not usually stay at bay for long. Halford had always been determined—“a 90-hours-a-week sort of researcher,” as his wife, Melanie Halford, puts it. The cancer diagnosis only seemed to harden his focus. Others had tried, and failed, to develop a herpes vaccine, but Halford was convinced that his method—using a live, attenuated form of the virus—would succeed. He would use whatever time he had left to show he was right.

The trouble was that the institutional gatekeepers of science—the agencies that fund research—didn’t view his work with the same urgency. He wasn’t getting the grants he thought he deserved. He felt “alone in the wilderness,” Melanie says, but also certain that his formula held unique promise. The question that drove him was not the practical “Will this work?” but rather an ethical one: “If I can help people suffering from herpes, isn’t it my duty to do so?” Melanie told me that “it was completely obvious to him what needed to be done.” Halford decided to barrel forward on his own unorthodox terms.

People with herpes who scoured the internet for research on their condition often discovered Halford’s scientific writing and blog posts, which combined technical information and a wry frustration with the status quo. Several readers reached out to Halford for help. A woman named Carolyn, who ran a private Facebook group devoted to genital herpes, approached him in 2012, and a few months later, Halford got back in touch and suggested they talk by phone. “That’s when he told me he had been fighting cancer and felt he needed to find out if the vaccine he developed could be therapeutic,” Carolyn recalls. In his animal research, Halford was testing whether his attenuated virus could prevent herpes, but scientists were also studying whether herpes vaccines could treat the disease. Carolyn suffered from debilitating nerve pain, and when Halford asked if she wanted to try the drug, she says, “I felt like I had hit the lottery.”

Carolyn suffered from debilitating nerve pain, and when Halford asked if she wanted to try the drug, she says, “I felt like I had hit the lottery.”

Through his blog and Carolyn’s Facebook group, Halford found other potential research subjects. He told them that the vaccine carried risks, as all vaccines do, but claimed that his formulation was “much safer” than those used for measles, mumps, polio, and chicken pox. Halford reassured the skeptical that he had tested his formula on himself, despite being weak from chemo, and had injected family members, and that they had “no side effects,” says Carolyn, who did not want to give her last name because of the stigma attached to ­herpes. Halford answered the potential volunteers’ questions by email and in long phone conversations. He sent at least one of them pictures of the large, red welts that were likely to develop on their calves around the injection site.