Twenty-four Month Efficacy of a Maternal Short-course Zidovudine Regimen to Prevent Mother-to-child Transmission of HIV-1 in West Africa

Objective: To assess the 24 month efficacy of a maternal short-course zidovudine regimen to prevent mother-to-child transmission (MTCT) of HIV-1 in a breastfeeding population in West Africa.

Methods: Data were pooled from two clinical trials: DITRAME-ANRS049a conducted in Abidjan, Côte d'Ivoire and Bobo-Dioulasso, Burkina-Faso and RETRO-CI, conducted in Abidjan. Between September 1995 and February 1998, consenting HIV-1-seropositive women were randomly assigned to receive zidovudine (300 mg) or placebo: one tablet twice daily from 36-38 weeks' gestation until delivery, then in DITRAME only, for 7 more days. Paediatric HIV-1 infection was defined as a positive HIV-1 polymerase chain reaction, or if aged > or =15 months, a positive HIV-1 serology. Cumulative risks (CR) of infection were estimated using a competing risk approach with weaning as a competing event.

Results: Among 662 live-born children, 641 had at least one HIV-1 test. All but 12 children were breastfed. At 24 months, overall CR of MTCT were 0.225 in the zidovudine and 0.302 in the placebo group, a 26% significant reduction. Among children born to women with CD4 cell counts < 500/ml at enrollment, CR of MTCT were similar, 0.396 in the zidovudine and 0.413 in the placebo group. Among children born to women with CD4 cell counts > or =500/ml, CR of MTCT were 0.091 in the zidovudine and 0.220 in the placebo group, a significant 59% reduction.

Conclusion: A maternal short-course zidovudine regimen reduces MTCT of HIV-1 at age 24 months, despite prolonged breastfeeding. However, efficacy was observed only among women with CD4 cell counts > or =500/ml. New interventions should be considered to prevent MTCT, especially for African women with advanced HIV-1 immunodeficiency.