New ACTG 076 Analysis Emphasizes Importance of Offering AZT Therapy to all HIV-Infected Pregnatn Women

11/25/96 10:35 %9301 496 0019 NIH NEWS-2B25/31 [A004/005

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genetic material -- HIV RNA -- in a person's bloodstream. These levels of virus are also
referred to as a person's "viral burden" or "viral load." In addition, the researchers cultured the
mothers' blood samples for the presence of HIV.
In both the AZT and placebo groups, perinatal transmission occurred within a wide
range of maternal HIV RNA levels, including instances when women had undetectable levels of
HIV in their bloodstreams as well as when women had viral loads greater than 100,000 RNA
copies per milliliter of blood.
In the placebo group, a high maternal viral load at study entry or at delivery, or a positive
blood culture, was associated with an increased risk of transmission. Among the quarter of
women with the highest viral loads, the rate of transmission was more than 40 percent. The
investigators also found that transmission was more likely when a woman not receiving AZT
had a low CD4+ T cell count. However, even among 119 untreated mothers with CD4+ T cell
counts above 500/mm3, the transmission rate was 21 percent.
In the treatment group, AZT therapy reduced median maternal HIV RNA levels 1.7-fold
between study entry and delivery. This modest change, however could not account for the
substantially reduced transmission rate in the AZT group, a benefit that was observed
regardless of maternal viral load and CD4+ counts.
Background
Following the dissemination of ACTG 076 study results in 1994, the Public Health
Service published guidelines for the use of AZT to prevent perinatal HIV transmission and for
HIV counseling and voluntary testing for pregnant women. Other organizations in the public
and private sector also launched campaigns to translate the ACTG 078 findings into prevention
programs.
These efforts have been successful, according to a number of recent studies. For
example, in a national study conducted by the U.S. Centers for Disease Control and Prevention
(CDC), rates of HIV infection among infants born to HIV-infected women dropped from 21
percent before the 1994 PHS guidelines to 11 percent in 1995.
New data indicate that perinatal prevention efforts also have dramatically reduced AIDS
cases in children. On Nov. 21, 1996, CDC released in the Morbidity and Mortality Weekly
Report (MMWR) information that documents a substantial reduction in perinatally acquired

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