Bangkok – The minister of health had the first word but scientists had the last on the question of nevirapine at the International AIDS conference yesterday.

In a scientific session yesterday (Thursday) South African virologist Dr Lynn Morris showed that although there was high resistance to nevirapine six weeks after a woman had taken a single dose, this dropped to 14 percent after six months.

Morris said resistance to nevirapine was first reported four years ago, but that this did ‘€œnot impact on the ability of nevirapine to prevent the transmission of the virus to children’€.

She said the likelihood of resistance to nevirapine seemed to increase among women who had a high viral load (of HIV) and a low CD4 count, which implied that their immune system was weak.

Drawing recommendations from her findings, Morris said the use of Nevirapine to prevent mother to child prevention should be limited to a single dose only.

She said that multiple studies had showed that nevirapine was effective and that in the absence of suitable alternatives, nevirapine should be provided to prevent the mother to child transmission of HIV (PMTCT).

In a ‘€œlate breaker’€ session of the conference yesterday afternoon, Dr James McIntyre of the Perinatal HIV Research Unit at Chris Hani Baragwanath Hospital presented a study that suggested a possible alternative therapy for PMTCT.

In a small trial with only 61 mothers, McIntyre said researchers found that if a branded drug (Combivir), made up of the antiretrovirals AZT and 3TC, was added to a single dose of nevirapine, resistance to nevirapine dropped considerably.

If the combination therapy was offered for four days, resistance was found to be five percent. If the therapy was offered for seven days, resistance levels were 13 percent.

McIntyre said that the study was still in progress to see the different results between a seven-day regimen as opposed to four days.

The resistance to a single dose of nevirapine found in this study was 50 percent. However it was noted in discussion of McIntyre’€™s findings that this was a study of just 61 women and that this could not be considered an accurate rate.

A far more substantial finding was that nevirapine resistance was between 13 to 14 percent as cited by Dr Lynn Morris in her much larger study at two sites ‘€“ Soweto and Durban.

Concluding his presentation, McIntyre stressed that a single dose of nevirapine was still effective as a means of preventing the transmission of HIV from mother to baby. He added that his new study ‘€œmight be a feasible and affordable solution to lower resistance.’€

Last Sunday, opening the South African stand at the International AIDS conference, health minister Dr Manto Tshabalala-Msimang said government was concerned about resistance levels to a single dose of nevirapine, a regimen she said had been forced on government by civil society through a Constitutional Court case.

This claim was angrily rejected by the Treatment Action Campaign which said it knew that there were better regimens for PMTCT, and that the Constitutional Court judgment had not forced the public health system to use the single-dose nevirapine regimen.

In Western Cape public health facilities the PMTCT regimen uses a combination of nevirapine and AZT.

E-mail Sue Valentine