If World Aids Day on December 1st felt like a bit of a love-in over achievements to date against the disease, a Canada-based organisation has brought us earthwards with a bump. Aids-Free World, founded by the redoubtable Stephen Lewis and not known for pulling its punches, says in a statement that the UN's determination to be seen to be cutting the numbers of infants infected with HIV at birth is putting the health of mothers and babies at risk. UNAIDS absolutely refutes the charge.

Aids-Free World says that women are being given sub-standard treatment to prevent their HIV infection being transmitted to their baby. In some, but not all, countries, they are still being offered single-dose nevirapine, which in the early days of attempts to safeguard babies, was all that was available.

The charge against the UN is that it is counting this sort of flawed treatment - which would no longer be permitted in rich countries - as part of the statistics of success (53% of pregnant women with HIV are given drugs to prevent transmission to their babies, says this month's UNAIDS report).

Paul De Lay, deputy executive director of UNAIDS, clearly feels the attack is unfair. The figures they presented, he says, were the data available - in the report it was broken down by type of drug given.

"Whether that is a success or not depends how you view it. Does nevirapine prevented transmission? Yes it does. Does single dose nevirapine save infants' lives - officially three to four years ago it was the gold standard treatment? Yes it does," he says.

It's a rapidly evolving field, De Lay says. "Should we be accused of not using the most effective drugs? That's ridiculous," he says. It takes time to implement new scientific wisdom - but in fact, in HIV/Aids, things have moved incredibly fast. The guidelines came out only at the end of 2009, he points out. "It took the US two years to implement the initial long-term AZT drug regimen recommended at that time in the mid 90s."

In five or ten years' time, we are very unlikely to be using the drugs that are considered gold standard now, De Lay adds. Few would dispute that - least of all, one assumes, Aids-Free World. In fact, that's their point, I assume - that the faster we move, the more lives we save.