World AIDS Day holds a special significance this year, with 2010 witnessing the most dramatic breakthroughs in HIV prevention since the first days of the global pandemic, says UNSW Professor John Kaldor.

"From the beginning, the great hope has been a vaccine ... (and) some scientists and public health officials confidently predicted that an intensive research effort would see success within a matter of years," Professor Kaldor, from UNSW's National Centre in HIV Epidemiology and Clinical Research (NCHECR), writes in the Sydney Morning Herald.

"In fact, it was not until the first decade of the 21st century that vaccine trials began on a large scale, and the initial candidates fell very short of the mark. The most recent vaccine trial, completed in late 2009, showed some promise, but the results were borderline and will have to be replicated in new trials that could take another five years or more."

But Professor Kaldor says other strategies have shown far better results. They include the discovery in 2005 that circumcision could cut men's risk of infection by 60 per cent, and that a prevention product used by women, the so-called vaginal microbicide, could provide protection of about 50 per cent.

However, the best news came just last week - that highly effective drugs for treating HIV infection may also be useful in prevention, by providing a chemical barrier to thwart the virus taking hold.

"Men who took a daily pill cut their infection rates by more than three-quarters," Professor Kaldor says.

"While there are many questions still to be answered before the vaginal microbicide or oral prophylaxis become routinely available, this year for World AIDS Day we can really celebrate the endeavours of committed research teams, funding bodies, affected communities, and tens of thousands of trial volunteers without whom this progress could never have occurred."

To read the full opinion piece, go to the SMH website.