Offering earlier access to HIV medications is expected to help cut down the rate of new infections.

Pharmac's proposing spending some of a funding boost on widening the availability of anti-retrovirals.

At the moment people living with the virus are only prescribed them when their immune system has been sufficiently damaged.

That's a policy based on old science, reflecting a time when the treatments were considered toxic - and avoided until absolutely necessary.

New Zealand AIDS Foundation executive director Jason Myers said they are now far less toxic, and earlier access can help in the HIV prevention fight.

"If somebody can be on treatment, and achieve an undetectable viral load, then it drastically reduces their chances of passing HIV on," he said.

Dr Myers also said research shows a 53 percent reduction in serious illness or death for people who begin using them early.

He said that all of the world's science is suggesting that "immediate treatment beyond diagnosis is the best thing for the long-term health of an individual diagnosed with HIV."