Final data from a collaborative study conducted by the Centers for Disease Control and Prevention (CDC), Mahidol University, Bangkok, and the Ministry of Public Health in Thailand (MOPH) indicate that a short course of AZT given late in pregnancy and during delivery reduced the rate of HIV transmission to infants of infected mothers by half and is safe for use in the developing world. This therapy offers hope for the first practical solution for reducing mother-to-infant (perinatal) HIV transmission in developing nations.
CDC researcher Nathan Shaffer, M.D., presented the data at the 12th World AIDS Conference today in Geneva. Shaffer also spoke of the ongoing global efforts to make this prevention opportunity a reality in as many nations as possible. Efforts are still underway to determine what impact this therapy may have in nations with no feasible alternative to breast-feeding.
Prior to these findings, the only AZT regimen proven effective for perinatal HIV prevention was essentially out of reach for the countries in which over 90% of perinatal HIV infections occur. The AZT regimen used in the U.S. and other industrialized nations is costly and requires several months of treatment for the mother and the infant and an intravenous dose that is not feasible in many developing countries. In order for policy makers in developing nations to provide HIV-infected women a preventive therapy, they urgently needed conclusive scientific evidence that a practical treatment regimen was safe and effective.
By using a much shorter course during pregnancy, an oral dose rather than an intravenous dose during delivery, and no infant dose, CDC and Thai researchers evaluated a regimen that could be more realistically implemented. The regimen consisted of 300 mg of oral AZT twice daily from 36 weeks gestation until labor and every three hours from the onset of labor until delivery.
Of the 392 women enrolled, 194 received the short-course AZT regimen and 198 were in the control group. The short-course AZT regimen reduced transmission by 50%, from a rate of 18.9% in the control group to 9.4% with treatment. Since the preliminary results in February, CDC has worked in collaboration with the Joint United Nations Programme on HIV/AIDS (UNAIDS) and public health agencies worldwide to help translate these findings into health policy and practice. Numerous steps have been taken.
CDC immediately began working with collaborators to implement the short-course regimen at the Bangkok study hospitals. In addition, CDC is exploring with the MOPH how best to implement the regimen more widely in Thailand.
In March, UNAIDS convened an international meeting in which CDC participated to discuss the far-reaching scientific and policy implications of the findings.
In May, CDC brought together researchers, practitioners, and policy makers from across the globe to discuss ways to move forward with implementation and address remaining challenges.
As the health ministries of each country work to determine what these findings mean for them, numerous challenges remain ahead. While this short-course AZT regimen will contribute to reducing mother-to-child transmission of HIV in some developing nations, there is still a need for even simpler and less expensive solutions in areas where even this short-course regimen remains out of reach.
Additionally, in countries with no safe alternative to breast-feeding, the impact of transmission through breast-feeding after birth will still have to be considered. Estimates suggest that at least 273,000 infants worldwide are infected through breast-feeding each year. As public health agencies work to expand availability of the short-course regimen, efforts must also focus on developing new solutions to reduce transmission to infants after birth. CDC is committed to ongoing collaboration to help reduce the toll of HIV among children worldwide.