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South Africa has driven mother-to-child HIV transmission down to 4%
Carole Leach-Lemens, 2016-07-20 21:10:00
transmission (MTCT) of HIV at population level was just over 4% at 18
months follow-up in South Africa, Ameena Goga,
presenting on behalf of the South African prevention of mother-to-child
transmission (PMTCT) Evaluation Group, told participants at the 21st
International AIDS Conference (AIDS 2016) in Durban on Tuesday.
countries are working towards virtual elimination of mother-to-child
transmission, and the numbers of infants born with HIV or infected post-partum
have declined sharply since the introduction of combination antiretroviral
therapy for mothers – Option B and Option B+ – the effectiveness of PMTCT
programmes needs to be monitored in order to understand where infants are still
becoming infected and what can be done to drive down transmission.
Greater clarity about when infections are occurring after delivery can also help target interventions.
Data on national
18- to 24-month HIV-free survival, the gold standard measurement of PMTCT
programme effectiveness, is very limited in resource-poor, high HIV prevalence
settings. Dr. Goga cited just four studies undertaken since 2001.
(71%) HIV-exposed infants cumulative MTCT at 18 months was 4.3% (95% CI:
3.7-5%) as South Africa transitioned to Option B. 81% of MTCT and 67% of MTCT or death occurred within the first six
months after birth highlighting this critical time period for following-up
alive at six weeks and followed up between six weeks and 18 months HIV-free
survival was 93.7% (95% CI: 92.2-94.8%).
From 2012 to
2014 Dr. Goga and her colleagues conducted a national evaluation to measure
MTCT of HIV and HIV-free survival. This was at a time when PMTCT policy
transitioned from Option A to Option B. The primary research questions
comprised: among HIV-exposed infants what is the national population level risk
of MTCT or MTCT or death at six weeks, three, six, nine, 12, 15 and 18 months?
A closed cohort
of HIV-exposed infants was developed from a nationally representative cross-sectional
survey conducted between 2012 and 2013 to estimate early (four to eight weeks
postpartum) MTCT. The findings are to be published shortly. To
determine national estimates of 18-month HIV-free survival assuming a five per
cent MTCT rate and a five per cent death rate, a target sample size of 1620 was
African PMTCT Evaluation Group undertook three national surveys to measure
national PMTCT effectiveness: in 2010 when health policy provided maternal
zidovudine from 14 weeks into the pregnancy and single dose nevirapine during
labour and infant nevirapine during breastfeeding (Option A); in 2011-12 and in
2012-13 during which time policy changed to triple antiretroviral therapy for
all HIV-infected women during pregnancy and breastfeeding (Option B). [Option
B+ became policy in January 2015].
comprising public primary health clinics and community health clinics offering
immunisation services in all nine provinces were randomly selected.
blood spot specimens (iDBS) were taken at immunisation visits at four to eight
weeks of age and tested for exposure to HIV, and if positive tested for
infection using total nucleic acid polymerase chain reaction.
In the 9120
infant dried blood spot specimens taken at four to eight weeks of age the
national weighted infant HIV exposure prevalence and the national weighted risk
of early mother-to-child transmission was 33.1% (95% CI: 31.8-34.4%) and 2.6%
(95% CI: 2.0-3.2), respectively. Early MTCT across provinces ranged from 1.5%
infants, both antibody and maternal self-reported, were invited for
facility-based follow-up at three, six, nine, 12, 15 and 18 months. Caregivers
were interviewed and infants tested at each visit.
Of the target
sample comprising 2811 eligible HIV-exposed infants six per cent did not give
follow-up consent. At each time point 1600 to 1700 infants were followed up.
71% (1797) of
HIV-exposed infants were followed up at 18 months.
by three and six months was 2.7% (95% CI: 2.6-12.6) and 3.5% (95% CI: 3.1-4.4),
At nine, 12 and
15 months cumulative MTCT was 3.7% (95% CI: 3.2-4.6) 3.9% (95% CI: 3.4-4.7) and 4.1% (95% CI3.5-4.8),
MTCT rate at 18 months was 4.3% (95% CI: 3.7-5.0). The most rapid increase in
MTCT was seen within the first six months after birth slowly increasing
thereafter. Over 50% of postnatal MTCT occurred by six months. Postnatal MTCT
and intrauterine and early postnatal MTCT accounted for 39% and 61% of 18 month
most rapid increase in MTCT or death took place within the first six months.
Dr. Goga noted, included: the exclusion of infants without consent or who died
before six weeks of age; a closed cohort may underestimate MTCT and HIV-free
survival. The strengths of the study, Dr Goga concluded, lay in the nationally
representative sample and the fact that 94.1% of the eligible population
participated in the follow-up.