Thai Red Cross zidovudine donation program to prevent vertical transmission of HIV: the effect of the modified ACTG 076 regimen

Objectives To evaluate the impact of the modified ACTG 076 zidovudine regimen on the risk for vertical HIV transmission. Design Observational retrospective evaluation of a prospective cohort. Setting Thai Red Cross zidovudine donation program to reduce vertical HIV transmission. Patients HIV-infected Thai women and their offspring. Intervention The modified regimen consisted of 500 mg zidovudine daily during pregnancy and 300 mg zidovudine every 3 h during labor, taken orally, and 2 mg/kg zidovudine syrup four times daily for 6 weeks to infants. Main outcome measures Only infants with at least 1 HIV DNA polymerase chain reaction (PCR) result at age > or = 4 weeks were included. HIV infection was defined by having at least one positive PCR at age > or = 4 weeks. The transmission rate was calculated. Characteristics of women who did and did not transmit HIV to infants were compared. Results A total of 2891 women and their infants participated in the program and 726 infants of 719 women were included in the analysis. Forty-three infants were infected. The overall transmission rate was 6.0% (95% confidence interval, 4.4-8.0). There were no differences in maternal characteristics between transmitters and non-transmitters. The transmission rate in women who started zidovudine before 30 weeks' gestation was not significantly different from that in women who started zidovudine at or after 30 weeks' gestation: 5.7 versus 3.3%, respectively. Conclusions This modified zidovudine regimen is effective in reducing vertical transmission in a country with predominant subtype E infection. A donation program for preventing vertical HIV transmission can be implemented in developing countries, as in Thailand.