About a third of women who are given a single dose of nevirapine during childbirth will develop resistance to that class of drugs. Later, when their HIV disease progresses and they need treatment to stay alive, the antiretroviral regimens (ARVs) used in most developing countries may not work. Over 50 percent of the babies exposed to single-dose nevirapine will also develop drug-resistant HIV.It is particularly a problem when funds are shifting to PMTCT (sometimes at the cost of expanded ART) partly because of gains in coverage. The logic (which is largely sound) is that increasing PMTCT investment will close the last mile and make it possible (at least theoretically - see this post) to achieve the goal of no child born with HIV. If the PMTCT services that are available are taking the form of single-dose nevirapine and no more, that "last mile" may be a whole lot longer than people think.
This is not to say that PMTCT should not be prioritised but if the UN goals are able to be reached through single-dose nevirapine, the investment by governments and donors that these goals aim to stimulate will never produce the crucial and long-awaited outcomes of improving reproductive health services and health services for women and girls in general. Single-dose nevirapine is better than nothing (no matter what South Africa's ex-health minister may have believed) but broader PMTCT services are needed if this investment is to make a long-term difference.