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Current treatment options to prevent perinatal transmission of HIV
1St. George's Hospital, Blackshaw Road, London, SW17 0QT, UK. zuber.m@dial.pipex.com
Insights
Preventing mother-to-infant HIV transmission is crucial. Antiretroviral therapies like zidovudine (AZT) and nevirapine (NVP), alongside elective caesarean sections, significantly reduce HIV transmission rates in infants.
Area of Science:
- Virology
- Public Health
- Pediatrics
Background:
- Mother-to-infant HIV transmission is the primary infection route for children.
- Approximately 1600 infants contract HIV daily worldwide.
- Advances in understanding perinatal transmission enable effective interventions.
Purpose of the Study:
- To review interventions reducing mother-to-infant HIV transmission.
- To highlight the efficacy of antiretroviral therapies and non-pharmacological methods.
- To discuss the applicability of interventions in different economic contexts.
Main Methods:
- Review of key clinical trials (PACTG 076, PACTG 185, HIVNET 012).
- Analysis of pharmacological interventions (zidovudine, nevirapine).
- Evaluation of non-pharmacological interventions (elective caesarean section, breastfeeding prevention).
Main Results:
- Zidovudine (AZT) reduced perinatal HIV transmission by 67% (PACTG 076).
- Viral load is the sole independent factor for vertical transmission rate (VTR).
- Nevirapine (NVP) offers a simple, cost-effective intervention with proven efficacy.
- Elective caesarean section (ELCS) benefits are demonstrated, but unclear with HAART.
- Breastfeeding prevention is effective in resource-rich settings.
Conclusions:
- Combined interventions (AZT, ELCS, formula feeding) reduced VTR to ~1% in developed countries.
- Nevirapine (NVP) presents a promising, accessible option for developing nations.
- Limited safety data exists for HAART in pregnancy; a cautious approach is advised.
Abstract:
Mother-to-infant transmission is the primary means by which young children become infected with HIV. WHO estimates approximately 1600 infants become infected with HIV every day. Recent advances in identifying the factors determining perinatal transmission have allowed interventions to be made to reduce mother-infant transmission. Paediatric AIDS Clinical Trials Group (PACTG) protocol 076, the pivotal vertical transmission study demonstrated that zidovudine (AZT) in pregnancy could reduce perinatal transmission of HIV-1 by 67%. This was confirmed by PACTG 185, in pregnant women with more advanced disease, which also demonstrated that viral load was the only independent factor determining vertical transmission rate (VTR). More recently, results from several short-course antiretroviral trials have brought new hope, that effective preventative interventions can be extended to developing countries. Although most studies have involved shorter versions of PACTG 076, the latest finding from HIVNET 012 demonstrated a significant reduction in VTR using a two-dose regimen of nevirapine (NVP). This intervention is the simplest, least expensive regimen so far with proven efficacy in diminishing mother-infant transmission. Non-pharmacological interventions have also been studied recently. The benefits of elective caesarean section (ELCS) have been clearly demonstrated in recent studies. These studies were carried out at a time when highly active antiviral therapies (HAART) were not available. There is still no information as to whether ELCS provides any added benefit for women on HAART with an undetectable HIV viral load. Prevention of breastfeeding can also further reduce VTR. This strategy is more applicable to resource-rich countries where access to formula feeds is not a problem. Options to prevent perinatal transmission must take into consideration the economic climate in which the intervention is to be made. In developed countries, effective intervention with perinatal AZT, ELCS and exclusive formula feeding has already reduced the VTR to around 1%. There is limited safety data currently available on the use of other antiretrovirals in pregnancy. A cautious approach to the use of HAART in pregnancy is recommended at present.