In the Mbabane government hospital in Swaziland, Simba Thakuva carries out a routine check-up on a local woman and her baby. While she is HIV positive and receiving daily medication, a single dose of the antiretroviral drug nevirapine given to her child shortly after birth was able to prevent the infection being transmitted to her daughter.

Prevention of mother-to-child transmission (PMTCT) carries a small risk that children will develop a form of HIV resistant to nevirapine. But it is a simple, low-cost and powerful intervention that prevents the transmission of the mother’s infection in more than 80 per cent of cases. If prevention is the neglected twin of treatment in the battle against Aids, PMTCT is one of the most important and obvious areas deserving greater attention. “It is probably where we can make the most difference on prevention,” says Dr Thakuva.