Two-drug regimen can reduce vertical transmission risk to below 2%.

2004 MAR 4 - (NewsRx.com & NewsRx.net) -- Data from the Perinatal HIV Transmission Trial group (PHPT), a collaboration of researchers from Thailand, France, and the U.S., show that a simple two-drug regimen can reduce the risk of mother-to-child HIV transmission to below 2%, a result similar to those achieved using highly active antiretroviral therapy (HAART) during pregnancy.

In the absence of any intervention, 35% of the infants born to HIV infected mothers become infected. In 2003 alone, 2.5 million children were infected with HIV/AIDS, mostly through mother-to-child (vertical or perinatal) transmission; and over 500,000 children died of AIDS worldwide, making it one of the primary causes of child death in many countries, according to the World Health Organization (WHO).

With a simple combination of zidovudine (AZT) and one dose of nevirapine (NVP) for the mother at the time of delivery and for the baby soon after birth, along with formula-feeding, pediatric HIV infection could be almost eradicated, WHO says.

In Thailand, until recently the treatment for the prevention of perinatal HIV transmission was the administration of AZT during the third trimester of pregnancy, during labor and delivery, and to the newborns for 1 week, with formula feeding rather than breast feeding.

In 2001, the perinatal HIV prevention trial (PHPT2) began in Thailand to examine whether adding a single dose of NVP to the AZT regimen for mothers and infants would further reduce transmission without adding significant risk to mother or baby. Enrollment in the trial was offered to 1,844 HIV infected women receiving antenatal care in 37 hospitals throughout Thailand. If they consented, the mothers were randomly assigned to one of three groups: one group received the standard AZT treatment; the mothers in the second group received one dose of NVP at onset of labor in addition to the AZT treatment; mothers and infants in the third group received one dose of NVP in addition to the AZT treatment.

In May 2002, the Data and Safety Monitoring Board reviewed the first interim analysis based on all the data available at that time. Because of the significantly reduced rate of transmission in the groups receiving NVP, the investigators decided to close the AZT-only group and provide NVP to all women enrolled in the study. The trial was continued to determine if, in addition to giving one dose of NVP to the mother, it was also necessary to give one dose to the child.

Among women who delivered before interim analysis, the transmission rate in the group where both mother and infant received NVP was 1.1%; it was 6.3% in women who had received AZT only (p=0.00026, a highly significant difference). In the final analysis the rate of transmission was 2.0% ...