The NIH is infecting volunteers with flu to discover how the immune system works

Although influenza vaccines were first developed before World War II, basic questions--such as what antibody level to aim for--remain unanswered. The National Institutes of Health (NIH) is trying to close these knowledge gaps with the help of 100 healthy adults who are willing to be infected with flu.

NIH hopes to infect the 100 adults over the next year to improve understanding of how the body responds to the flu virus, the Associated Press reports. Infecting healthy volunteers in a controlled environment will allow researchers to track each step of the immune response, potentially revealing answers to some fundamental questions limiting the effectiveness of vaccines. Currently, we don't know the optimum antibody level, or whether at a certain amount illness is prevented or just milder.

Gaining this knowledge and incorporating it into vaccine development could improve the efficacy of flu vaccines, which in observational studies have failed to protect half of high-risk groups from the virus. "It's all going to add up to a better understanding of what you need to have to be protected against the flu," University of Rochester Medical Center flu specialist Dr. John Treanor told AP. NIH has already begun building this understanding by infecting the first groups to join the trial.

A notable early finding is that some people with low antibody levels didn't get sick, suggesting another mechanism is involved. The researchers hope to get a clearer picture by infecting people with varying antibody counts and vaccination statuses. Finding people willing to be infected is one potential stumbling block, but NIH is offering participants $3,000 to sweeten the deal. In return, enrollees--who can't be from high-risk groups--must spend at least 9 days in an NIH isolation ward.

Patients only receive a mild dose of the virus--and must no longer be contagious to be released--but some are still concerned about the safety risks. "I received a very scolding email from my mother [about signing up]," Daniel Bennett, a 26-year-old restaurant worker from Maryland, said.

- read the AP feature