A single dose of nevirapine is given to the mother before birth and to her baby after birth. The research in Uganda, completed in 2004 by the United States National Institute of Allergy and Infectious Diseases, indicated that taking even a single dose could create a drug-resistant HIV strain in some women and babies.
The Zambian study at the Centre for Infectious Disease Research examined 4,552 women receiving HIV/AIDS treatment, including 445 who had been given a single dose of nevirapine to prevent mother-to-child HIV transmission. After one year there was no significant difference in mortality or serious illnesses between women who had taken nevirapine and those who had not, according to Benjamin Chi, leading author of the report.
"Our study was conducted in the real-world setting of an urban, public, antiretroviral therapy programme in Zambia, and indicates that women who have previously used nevirapine to prevent perinatal transmission do not have worse clinical outcomes than women without this exposure," Chi was quoted as saying in a press release by the Elizabeth Glaser Pediatric AIDS Foundation, which funded the study.
"Additional follow-up is needed, but we are encouraged that women who take steps to protect their babies from HIV with nevirapine prophylaxis are not substantially jeopardising their own health," he commented.
The Ugandan study found that despite creating resistance, nevirapine was a safe and effective drug for preventing mother-to-child transmission and stood by its findings in the face of international media allegations of "flawed" results, failure to disclose safety concerns and staff misconduct.
A study of Thai women in July 2004, published in the New England Journal of Medicine, also showed that some women who received a single dose of nevirapine could harbour HIV that was resistant to the drug.
The Zambian study did find a possible risk of treatment failure in a small group of HIV-positive women who started taking ARVs less than six months after taking a dose of nevirapine to prevent transmission to their child. Chi said these women had likely had more advanced HIV and should have been started on a full regimen of ARV therapy before giving birth.
"HIV-positive pregnant women who might need treatment very soon after delivery should be considered for full anitretroviral therapy during pregnancy," said Dr Cathy Wilfert, co-author of the study. "Not only does this treatment limit resistance and keep infected mothers alive, but full combination therapy has the added benefit of providing very effective HIV protection for babies."
Without ARVs, a pregnant woman has a 20 percent to 45 percent chance of giving birth to an HIV-positive infant. According to UNAIDS, fewer than 6 percent of pregnant women in sub-Saharan Africa have access to a prevention of mother-to-child HIV transmission service.
Following the Uganda study, the World Health Organisation reaffirmed its support for the use of nevirapine in prevention of mother-to-child transmission programmes.
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