Postnatal HIV Transmission Seen After Infant Prophylaxis Stopped

Anthony J. Brown, MD

November 13, 2009

November 13, 2009 — A large study of infants uninfected with HIV at 14 weeks of age shows that transmission of the virus through breast milk occurs after extended antiretroviral prophylaxis is stopped.

The results suggest that infant prophylaxis is only effective while the prophylactic agents are being administered, Dr. Taha E. Taha, from Johns Hopkins Bloomberg School of Public Health, Baltimore, and colleagues state. Thus, added preventive measures are required for the duration of infant breast-feeding.

The researchers also found that treating mothers with highly active antiretroviral therapy (HAART) had a beneficial effect on postnatal HIV-1 transmission. "Receipt of HAAART after 14 weeks post partum by women who require therapy for their own health substantially reduced infant HIV infection after completion of the 14-week extended prophylaxis in infants," they note.

Using data from the Post-Exposure Prophylaxis of Infants trial in Blantyre, Malawi (PEPI-Malawi), the investigators assessed the association between HIV-1 transmission and maternal HAART following infant antiretroviral prophylaxis.

According to their report in the November 15 issue of the Journal of Infectious Diseases, breast-feeding infants of HIV-infected mothers were randomly assigned at birth to receive single-dose nevirapine plus 1 week of zidovudine (control), the control regimen plus nevirapine to age 14 weeks, or the control regimen plus both nevirapine and zidovudine to age 14 weeks. In addition to infant HIV infection, maternal CD4 cell count and HAART use were assessed.

Maternal HAART use was categorized as follows:

--eligible for use, but untreated (CD4+ cell count <250 cells/microliter, no HAART);

--eligible and treated (CD4+ cell count <250 cells/microliter, HAART given); and

--ineligible (CD4+ cell count 250 cells/microliter or higher).

The rate of HIV infection and the link between postnatal transmission and maternal HAART use was determined among infants who were HIV negative at 14 weeks of age.

Of 2318 infants studied, 130 (5.6%) became infected with HIV. HAART was given to 310 (13.4%) mothers.

The HIV transmission rates for the HAART eligible/untreated, HAART eligible/treated, and HAART ineligible groups were 10.56, 1.79, and 3.66 cases per 100 person-years, respectively. Use of the drug cocktail by eligible women was associated with an 82% reduced risk of HIV transmission, after adjusting for infant prophylaxis.

"These findings demonstrate that maternal HAART, when given for health indications during the breast-feeding period, has the added benefit of reducing the risk of late transmission of HIV," the researchers state.

They add, however, that "proportional reductions in infant HIV infection associated with maternal HAART for eligible women after cessation of infant prophylaxis at 14 weeks did not differ significantly between the control arm (68%) and the extended prophylaxis arms combined (89%)."

Among women who do not require HAART for their own health, "it is unclear how to optimally lower the risk of postnatal transmission," the authors state.

In settings where early weaning and formula feeding isn't possible, two options can be considered, they say. The first is to extend the infant's prophylaxis for two years, and the second is to give HAART to ineligible infected nursing women solely for the purpose of preventing HIV transmission to their infants.

"The choice between infant prophylaxis and maternal HAART for healthy women should take into account short- and long-term efficacy, safety, and cost," the investigators conclude.

J Infect Dis. 2009;200:1490-1497. Abstract

Reuters Health Information 2009. © 2009 Reuters Ltd.

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