Experts at an international HIV/AIDS conference in Winnipeg say researchers around the world are closer than ever to finding a vaccine against the virus.

Frank Plummer, director of Winnipeg's National Microbiology Laboratory, said he expects to see a vaccine in his lifetime.

"I'm confident that we will get there eventually," Plummer said. "It's not a simple problem. If it was, we would have done it already."

He said there are cases around the world of people who have had contact with the virus but haven't become infected. Plummer said some of that is luck, but it may also be due to natural immunity.

Case studies shared

Case studies were shared at a gathering of about 75 international experts at the conference.

Researchers at the conference pointed out that many breastfeeding infants who are born to HIV-positive women escape infection. Some groups of sex-trade workers who are repeatedly exposed to the virus also appear to be immune. 

'We don't understand it fully yet and that needs to be expanded. We don't understand how to produce it artificially, which is what a vaccine is all about.' —Frank Plummer

"Sometimes that's because of luck but sometimes that's because, I believe, they're immune in some way to HIV," Plummer said. "We don't understand it fully yet and that needs to be expanded. We don't understand how to produce it artificially, which is what a vaccine is all about."

In September, researchers announced that a two-vaccine combination cut the risk of becoming infected with HIV by more than 31 per cent in a trial of more than 16,000 volunteers in Thailand.

Canada's chief public health officer, David Butler-Jones, said some of the greatest vaccine discoveries have come from figuring out natural immunity.

"The original vaccine for smallpox was a recognition that milk maids who had cowpox were not susceptible to smallpox," he said.

Although some of the world's great minds are grappling with the virus, Butler-Jones said it is a very difficult illness to crack. People are capable of developing antibodies to HIV/AIDS but they aren't enough to protect against the virus, he said.

"It is one of the great scientific and medical challenges moving forward. Every day we are one day closer but exactly when that day will come, it's impossible to predict," Butler-Jones said. "The sooner, the better."

According to a 2008 United Nations report on the global AIDS epidemic, 33 million people were living with HIV in 2007. Two million people died of causes related to the disease that year.