South Africa is roundly praised for the rate of mother-to-child transmission which has plunged from 8% in 2008 to an estimated 2.7%, in 2011 (Medical Research Council survey) and is continuing to fall. However, experts are questioning whether this indicator is able to provide us with important information about postnatal HIV transmission, the transmission that happens once the baby has been born HIV-negative.

Dr Andrew Boulle, an HIV specialist at the University of Cape Town, says that the key message is encouraging: that there has been a dramatic decline in on-programme transmission. He adds that in the Western Cape “half of our new diagnoses are made in hospitals in sick children who are not measured by the PMTCT (prevention of mother-to-child transmission) programme.” “It is still a great success, but there is more to still be done than is apparent from the routine programme data.”

“As we get to these low numbers of transmissions, the relative importance of the pockets of missed patients become more important. Even if 5% of HIV-infected patients skip HIV testing, given the 10 times higher transmission without prophylaxis, they could contribute an extra 50% of infections not measured by the PMTCT programme.”

Experts agree that postnatal transmission is an important area of concern. Dr Vivian Black Director for Clinical Programmes at the Wits Reproductive Health and HIV Institute says that it is important for us to start reaching children who are not being tested at six weeks.

She agrees that it is very clear that we do not know what the health outcomes are for infants after six weeks. The lack of mother and infant follow-up is a massive weakness in South Africa’s PMTCT programme. If we are to fully realise the objectives of the NSP, then addressing this issue is critical.

Dr Leigh Johnson, an epidemiologist from the University of Cape Town, says that none of the indicators we have “tell us anything about the extent of postnatal transmission (transmission through breastfeeding).” “Although it’s very encouraging that we’ve made so much progress in reducing perinatal transmission (immediately before and after birth)” Johnson says, “it’s worrying that we have so little information on the extent of postnatal transmission.” Researchers have attempted to conduct postnatal follow up of HIV exposed infants who tested HIV negative at six weeks in order to measure postnatal transmission but maintaining a large cohort of infants across all nine provinces, where high mobility of mothers and infants is common, is challenging and expensive.

Considerable challenges remain

Writing in the District Health Barometer, Linda Mureithi from the Health Systems Trust, and Professor Gayle Sherman from the National Health Laboratory Service, caution that despite the success of South Africa’s PMTCT programme so far, we still face considerable implementation challenges. Important components need improvement, such as ensuring early antenatal clinic attendance and early infant diagnosis, the integration of PMTCT services into primary health care, and the provision of antiretroviral (ART) services to patients diagnosed with HIV. Data quality must also be improved in order to monitor progress.

Current polymerase chain reaction (PCR) testing at six weeks mainly identifies perinatal transmission – the HIV transmission that happens before or during birth. Babies born to HIV-positive mothers typically test HIV-positive on a standard antibody test because their blood contains HIV antibodies from their mothers for several months after birth. For this reason, babies are given a special PCR test that can [identify HIV in the blood within two to three weeks of infection and therefore] determine whether they themselves have HIV.

Johnson says that data from the District Health Barometer does not tell us enough about the proportion of HIV-positive mothers receiving different forms of antiretroviral prophylaxis antenatally and perinatally [and how this impacts on transmission rates].

The District Health Barometer 2012/13 gives a coverage rate of 82% for ART in pregnancy which appears to be an over estimate – the SAPMTCTE (South African PMTCT Evaluation) survey found 46% ART coverage in 2011.

Dr Ameena Goga, one of the main authors of the SAPMTCTE and Specialist Scientist at the Medical Research Council shares Johnson’s concerns.

She says that data from the National PMTCT evaluation (still in the process of being published as peer-reviewed papers) shows that:

• South Africa has reduced early (4-8 week) transmission to 3.5% with dual therapy introduced in 2008 and to 2.7% with an improved PMTCT regimens introduced in 2010 acquisition of HIV infection during pregnancy is high – in 2010 and 2011 surveys 4% of mothers reported negative but had HIV exposed infants by six weeks post-delivery transmission seems similar between mothers receiving longer term dual prophylaxis and ART (i.e triple therapy as treatment)
• Although South Africa has introduced the new ART regimen in April 2013, Dr Goga notes that its effects on mother-to-child transmission are still unknown. She cautions that rather than looking at transmission only, “we really need to look at child survival and in future need to add child development. I think this should always be a very strong message as we aim to build future generations”

Reaching a plateau

Dr Goga believes that South Africa will reach a plateau shortly at which greater and perhaps different investment will be needed to achieve further reductions in transmission. “It’s not only about the drug regimen, but co-morbidities; placental factors and so on will start coming into play as soon as the bulk of transmission is reduced. There is little available data showing what happens after six weeks post-delivery.

Goga notes that researchers are beginning to investigate such issues. In an article published in the journal AIDS this year, for example, Kate Kerber and colleagues sought to analyse trends in the mortality rate of under-5s in South Africa (1990-2011), and the contribution of AIDS in particular to these deaths. Estimates were reviewed using three nationally-used models for estimating [the number of] AIDS deaths in children.

Although different results were reported for each model, the trends revealed were similar, and showed that the mortality rates peaked at around the year 2005. AIDS as a cause of child deaths peaked between 37% and 39% in the period 2004-2005, and this level has since declined.

South Africa was one of only four countries in 2005 with a mortality rate for under-5s that was higher than the 1990 Millennium Development Goal baseline. In the past five years, the country has achieved a rate of reduction of child mortality exceeded by only three other countries.

The researchers ascribe this rapid success to the scale-up of South Africa’s PMTCT programme and, to a lesser degree, the expanded roll-out of ART.

“Emphasis on these programmes must continue, but failure to address postnatal transmission as well as other aspects of care including integrated high quality maternal and neonatal care means that the decline in child mortality could stall,” they add.

Breastfeeding is still the recommended feeding choice for all mothers, including those who are HIV-positive. South Africa’s exclusive breastfeeding rate is among the bottom ten globally and has suffered from mixed messages around best practices. “We all agree that postnatal transmission is now going to be the next big issue to tackle, but hopefully we can do so without confusing the breastfeeding messages again,” adds Kerber.

While there is agreement that South Africa’s PMTCT programme is a best practice model, many questions remain as to what happens once the mother has given birth – in essence we know very little.

[box]NSP TARGETS

Strategic Objective 2

• Reducing transmission of HIV from mother to child to less than 2% at six weeks after birth and less than 5% at 18 months of age by 2016.
• This includes strengthening the management, leadership and coordination of the PMTCT programme and ensuring its integration with maternal- and child health programmes.
• TB screening will be integrated into the PMTCT programme.
• In addition, screening and treatment of syphilis will be strengthened to eliminate neonatal syphilis.

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