Last week researchers announced that a new com­bi­na­tion vac­cine has been shown to greatly reduce the risk of HIV infec­tion. Here Steven Leonard, assis­tant pro­fessor of phar­macy in the depart­ment of phar­macy prac­tice and a spe­cialist in infec­tious dis­eases, answers ques­tions about what the results ofthis ground­breaking study mean for AIDS patients and HIV/​AIDS research.

What did researchers dis­cover, and how do their find­ings fit into the big pic­ture of finding a cure for HIV/​AIDS?

By cut­ting the risk of infec­tion by more than 30 per­cent, this study is the first to show any ben­efit what­so­ever from an HIV vac­cine. It did not com­pletely pre­vent HIV infec­tion, and more work will be needed before a vac­cine would be avail­able, but it is a major step forward.

In the last 25 years since it was deter­mined thatthe HIV virus causes AIDS, there have been more than 25 mil­lion deaths world­wide as a result of the dis­ease. Each year there are 2 to 3 mil­lion new cases. While ourmeans to combat the infec­tion and extend people’s lives has greatly improved, there is still no cure. So our ability to pre­vent the infec­tion is key in fighting HIV.

How does this study differ from pre­vious studies?

Aside from being the first to show any effi­cacy, it dif­fers in that it was a com­bi­na­tion of two vac­cines given in a sequence of six immu­niza­tions over the course of six months. It was based on HIV strains that com­monly cir­cu­late in Thai­land, where the study was con­ducted. At this time it’s unclear how these vac­cines would work else­where in the world.

The recent trial was con­ducted on a test group of 16,000 vol­un­teers. How does the size ofthis trial com­pare with pre­vious tri­alsof other vaccines?

It is the largest HIV vac­cine study ever. In terms of enroll­ment, it is sim­ilar in scope to recent studies of vac­cines against human papil­lo­mavirus (HPV) for the pre­ven­tion of cer­vical cancer. This lends a good deal of cred­i­bility to the results.

What is the like­li­hood ofthe HIV­vac­cine becoming avail­able to the public—particularly to people in devel­oping nations who are most sus­cep­tible to the virus?

I believe that if a suc­cessful vac­cine becomes avail­able we will see a world­wide effort of unprece­dented scope to ensure that the vac­cine is made avail­able to everyone, including those in devel­oping nations where the impact of the dis­ease has been the most severe. It would be one of the most impor­tant advances in public health during our lifetime.

Will we ever be able to vac­ci­nate against HIV/​AIDS with the suc­cess rate that we have for vac­ci­nating against, say, the mumps or polio?

Before these results were released I was skep­tical that a vac­cine for HIV/​AIDS could be devel­oped. My doubts stemmed from the sig­nif­i­cant sci­en­tific dif­fi­cul­ties pre­sented by the virus and the fact that two pre­vious large-​​scale HIV/​AIDS vac­cine trials failed to show any ben­efit. While this vac­cine didn’t pre­vent HIV infec­tion com­pletely, it does give a reason to hope that a suc­cessful vac­cine could be devel­oped in the future.