Preventing HIV in Babies Could Harm Moms

Stopping mother-to-child transmission may come at a price

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By
HealthDay Reporter

SATURDAY, July 10, 2004 (HealthDayNews) -- In fighting an epidemic of HIV in the developing world, what's more important: Sparing newborns infection with the virus, or helping their HIV-positive mothers live longer, healthier lives?

That's the dilemma facing health experts debating the results of two new studies to be presented at an international AIDS Conference in Bangkok, which starts on Sunday.

One study found that babies born to women given a single dose of the drug nevirapine during labor were at much lower risk of becoming infected with HIV.

But another study found that protecting babies in exactly this way reduces their mother's ability to fight HIV over the longer term.

"I think these data are concerning," said Dr. Heather Watts, a medical officer at the branch of Pediatric, Adolescent and Maternal AIDS of the National Institute of Child Health and Development, which helped fund both studies.

Watts said the findings "don't necessarily mean that we shouldn't be using nevirapine to prevent mother-to-child transmission," however. She advocates creative solutions to the problem, including giving women with more advanced HIV disease better medicines to help them beat back the virus in the months after delivery.

The studies, to be published in the July 15 issue of the New England Journal of Medicine, were released early because they're being presented at the conference, which runs through July 16.

According to experts, more than 700,000 infants worldwide develop HIV infection each year, the majority contracting the virus from an infected mother during delivery. In developing countries such as Thailand, health officials try to keep maternal HIV transmission levels low by giving pregnant women the antiviral drug zidovudine, beginning in their third trimester.

In other countries, especially in Africa, daily zidovudine is less available. So health workers fall back on a single dose of another antiviral, nevirapine, given to mothers at the onset of labor as a means of temporarily reducing a baby's exposure to the virus during delivery.

But what about using both these strategies together?

In their study, researchers led by Dr. Marc Lallemant of the Harvard School of Public Health tracked rates of HIV infection in infants born to 1,844 HIV-infected Thai women.

As is standard in Thailand, all of the women received zidovudine beginning at 28 weeks gestation. However, in a third of deliveries, the mother also received a single dose of nevirapine at the onset of labor, as did her newborn soon after delivery. In another third of deliveries, only the mother received the nevirapine, while in the last third, the mother and her baby received only zidovudine.

According to the researchers, an extremely small number -- just 1.1 percent -- of infants in the zidovudine/nevirapine group tested positive for HIV in the weeks after birth. In contrast, 6.3 percent of babies in the zidovudine-alone group went on to test positive for the virus.

In his editorial, South African HIV/AIDS researcher Dr. Hoosen Coovadia called the nevirapine-linked reduction in mother-to-child transmission "astonishing." He pointed out, as well, that the nevirapine-zidovudine combo treatment is currently recommended by experts at the World Health Organization as the "most efficacious regimen" for preventing mother-to-child transmission of HIV.

However, the results of a second study cast a pall over those findings.

In the second study, researchers led by Dr. Gonzague Jourdain, also of Harvard, followed the health status of the same 1,844 Thai women for six months after their respective deliveries.

They report that women who received a single dose of nevirapine during their labor were much more likely to develop viral resistance to nevirapine and the nevirapine-like family of drugs used to fight HIV.

By six months, less than half (49 percent) of women given nevirapine during delivery showed evidence of successful viral suppression, meaning that the virus was multiplying despite the use of antiviral drugs.

By comparison, among women who did not receive nevirapine during their delivery, 68 percent continued to maintain healthy suppression of the virus.

"The issue of nevirapine resistance within the virus has been detected in other studies," Watts said, "but this is really the first study to look at the longer term."

"If you give any medication and there's resistant virus, the medication knocks out all the non-resistant virus and allows the resistant virus to grow," she explained. So women exposed to nevirapine during delivery appear to develop a resistance to these types of HIV medications earlier, she said -- even though the drug may have spared their child the tragedy of infection with HIV.

Still, Watts said, this doesn't mean zidovudine-nevirapine combination therapy should be dismissed. She pointed out that women who develop resistance tended to be in a more advanced stage of HIV disease, even in the months before their delivery.

"Therefore, one way to attack this would be to offer highly active antiretroviral therapy for these women who would need it most," she said. Providing these most vulnerable women with a combination of powerful drugs might give them the added defense they need to fight off HIV, she said.

Watts also wondered if the study period was long enough to assess whether the virus might recede again, if given a year or two.

"We need more data as to the long-term impact of [zidovudine-nevirapine therapy]," she said. "We need to evaluate what the impact is and, if it's substantial, to have other drug regimens available for those women that require that treatment."

The studies come amid a steady jump in infections. The United Nations said Friday that women are experiencing a dramatic rise in HIV in part because poverty has robbed them of the confidence to demand safe sex, the Associated Press reported.

More information

Learn about what's being done to stop mother-to-child transmission of HIV from the World Health Organization.

SOURCES: Heather Watts, M.D., medical officer, Pediatric, Adolescent and Maternal AIDS branch, National Institute of Child Health and Development, Bethesda, Md.; July 15, 2004, New England Journal of Medicine

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