Simplified Antiretroviral Therapy During Pregnancy Effective and Acceptable Among Thai Women, CDC Study Says

A Thailand Ministry of Public Health pilot program designed to test and treat pregnant women for HIV with a simplified zidovudine regimen reduced the risk of mother-to-child viral transmission from 30% to 10%, CDC researchers reported in the July 20 issue of Morbidity and Mortality Weekly Report. Routine prenatal counseling and voluntary HIV testing were integrated into Thai public prenatal services by July 1998. As part of a pilot program to determine if "simpler and more cost-effective interventions" can prevent vertical transmission of HIV with the same efficacy as the extended zidovudine prophylaxis used in wealthier nations, HIV-positive Thai women were offered zidovudine from 36 weeks gestation through labor and free infant formula for one year after birth (Morbidity and Mortality Weekly Report, 7/20). Current U.S. guidelines recommend beginning zidovudine treatment between 14 and 34 weeks gestation and continuing through labor (Public Health Service Task Force Perinatal HIV Guidelines, 5/4).

Results
Between July 1998 and June 2000, about 1% of 104,393 new prenatal clinic patients tested HIV-positive, and at delivery 69% of 922 HIV-positive women had received zidovudine prophylaxis. Eight percent of 229 infants whose mothers had taken zidovudine were born with the virus, compared to 14% of 64 infants born to mothers who did not use zidovudine. Overall, the estimated vertical transmission rate was 10%. Researchers noted that HIV testing, HIV results documentation and zidovudine use "increased significantly" during the study period. To evaluate program coverage, acceptability and influence, researchers interviewed two groups of women: women who had given birth within two months of the interview and whose delivery record did not include HIV status documentation and those who had given birth within 12 months of the interview and were documented to be HIV-positive. Of the 215 women whose HIV status was not recorded at the time of delivery, 54% said they had an HIV test during pregnancy, with 71% of the women tested reporting that they knew their test result and those results were all negative. Of the 162 HIV-positive women, 94% knew they carried the virus before delivery, 98% reported having received post-test counseling and 79% had taken zidovudine to reduce the risk of vertical transmission. Eighty-nine percent of women taking the drug said they did not skip a single dose of medication and only 1% refused to take the drug. All of the HIV-positive women said they used the infant formula provided through the study, although 6% noted that they breastfed for a "short period" of time. In comparison, 95% of the women whose HIV status was not recorded at delivery reported breastfeeding their infants.

HIV Prevention Potential
In an editorial note, the CDC says that the program interventions were "acceptable to most women" and that the "interventions to reduce mother-infant HIV transmission can be implemented successfully on a large scale in Thailand." On the basis of clinical trials and pilot programs in Thailand between 1996 and 1999, the Ministry of Public Health began a national program to prevent vertical transmission in 2000. The editorial states, "On the basis of the estimated 20% decrease in mother-infant HIV transmission among the 15,000 babies born to HIV-infected women, the Thai national program has the potential to prevent approximately 3,000 infant HIV infections each year." The note concludes, "In addition to reducing mother-infant transmission, such programs can improve voluntary counseling and testing services, reduce the sexual transmission of HIV, promote informed decisions about childbearing, and link HIV-infected persons to health and social services" (Morbidity and Mortality Weekly Report, 7/20). Also available in this issue is a list of the 25 most notable HIV/AIDS reports published in MMWR.