The modest success reported by HIV vaccine researchers in Thailand last month is credited with reinvigorating the HIV vaccine field, even as the early results are under scrutiny at an international conference.

Almost 1,100 scientists are attending the AIDS Vaccine 2009 conference in Paris. Many others were shut out, because there wasn't enough room for all of those interested in attending.

'Political support and budget support for AIDS activities, in many countries, including Canada, seems to slip.'— Peter Piot

On Sunday, heads of major vaccine research groups from around the world met to talk about the results of the Thai trial, which reported 31 per cent of 16,000 volunteers from high-risk groups who were vaccinated were protected from infection.

"If the data holds up that there is evidence of protection … that's a first after 26 long, hard years, and therefore will be a landmark result," Canadian Dr. Alan Bernstein, who heads the Global HIV Vaccine Enterprise, told CBC News. His organization is co-hosting the conference.

On Tuesday, researchers will release more information from the trial. Early reports suggest the latest data won't show the same degree of success as the early results.

In recent years, interest in vaccine development has also lagged.

Vaccine cheaper option

Ironically, new and successful drug treatments may have held back work on vaccines, and pharmaceutical companies have largely withdrawn from the effort.

Antiviral drugs for HIV cost billions of dollars, and have terrible side-effects. Their cost is crippling health systems in some developing countries, said Bernstein, and many infected people go without treatment.

"Even with all the billions being put into drugs, only about 40 per cent of the people who need drugs are getting access to them," he said.

A vaccine is still seen as the cheapest and most effective way to deal with HIV, but the global economic downturn threatens to derail the momentum.

"If you look at what happened in just one year, we have a 10 per cent drop in public and private spending on vaccine research," Michael Sidibe, with UNAIDS in Geneva, told CBC News.

As 7,000 more people become infected with HIV worldwide every day, researchers said they're worried that budgets for HIV research will be trimmed even further in 2010, as governments struggle to resuscitate their economies.

"Political support and budget support for AIDS activities, in many countries, including Canada, seems to slip," said Peter Piot, director of the Institute for Global Health at Imperial College in London.

Piot pointed to the massive bail outs for banks and insurance companies as proof that the money exists.

The conference runs until Thursday.