The plague-bearer

In 2023 a bioengineered pathogen escaped from a military laboratory. It was highly contagious and virulent. Humans had no resistance to the pathogen. If infected, the fatality rate was 100%. 

Civil authorities resorted to ruthless, desperate quarantine measures. Anyone suspected of contracting the disease was burned alive by soldiers and police armed with flamethrowers. Major population centers were nuked with neutron bombs. But it was a losing battle. The human race was facing imminent extinction. 

Yet years before the existential threat emerged, there was a young man by the name of Josh. As a teenager, he discovered that if he laid hands on sick family member, he could extract and absorb the illness. By transferring the illness to himself, he destroyed it.

This was, however, a closely-guarded family secret. If Josh's abilities as a healer became well-known, he'd never have a moment's rest. His reputation would curse him to be inundated by countless desperately sick men and women, or parents bringing their hopelessly sick children. It was far too much for one man to handle. 

But after the outbreak, he sacrificially volunteered to heal the sick. The task was overwhelming. When the military got wind of his gift, he was abducted and taken to a secure facility, where he was tested. After some experiments, they discovered that if his blood was infected with the pathogen, it developed antibodies that destroyed the pathogen. Transfusions of his blood cured the infected. And their blood developed the same antibodies. By replicating the antibodies, scientists devised an antidote. 

He saved the human race through his vicarious healing abilities. But his fame as a healer made his own life unendurable. He had no respite. He couldn't go into hiding because he was too recognizable. And too many eyes were tracking his every movement. Having a wife and kids was out of the question, and his freedom was constantly endangered by fanatics who sought to kidnap him for their own use. He felt like a hunted animal. He died at 23 when he was swept downriver attempting to elude pursuers.