Among women on antiretroviral therapy (ART) prior to pregnancy, early mother-to-child transmission in Malawi’s Option B+ programme compares favourably to transmission rates observed in developed countries, Sundeep Gupta told participants on Tuesday at the Conference on Retroviruses and Opportunistic Infections (CROI 2016) in Boston, USA.
Dr Sundeep Gupta presented on behalf of the National Evaluation of Malawi’s PMTCT (prevention of mother-to-child transmission) programme (NEMAPP), a two-year cohort study comprising 1851 HIV-positive mothers of 4- to 12-week-old infants. Dr Gupta noted that among those women who either never started ART or stopped at any time during or immediately after pregnancy (5.5%), mother-to-child transmission in 4- to 12-week-old infants was almost tenfold higher than among women on ART during pregnancy, 20.3% and 2.9%, respectively, p < 0.001.
Mother-to-child (vertical) HIV transmission varied according to timing of ART. It is well known that the earlier in pregnancy the diagnosis is made or confirmed and treatment initiated, the better for the health of the mother and the greater the reduction in risk of HIV transmission to the infant. These findings contribute further. For example, vertical transmission among women starting ART in the first or second trimester was 4.1% compared to 13.3% among those starting treatment postpartum (after childbirth). And, among the 46.5% of women on ART prior to pregnancy, mother-to-child transmission was 1.4% compared to 20.3% among the 5.8% of women never starting ART.
The lifelong offer of treatment, regardless of CD4 cell count, to all HIV-positive pregnant and breastfeeding women, known as 'Option B+', was pioneered by Malawi’s Ministry of Health in 2011. It aimed to simplify the implementation of ART for prevention of vertical transmission and for the health of the mother, as well as preventing transmission horizontally (e.g. transmission to a sexual partner).
The Ministry of Health has documented improved clinical and programmatic outcomes following adoption of Option B+. Its implementation led to a seven-fold increase in women starting ART in the first year alone.
A CDC-funded operational research study, NEMAPP’s primary objective is to evaluate the effectiveness of the national PMTCT programme and measure the vertical transmission rate in age-based cohorts of HIV-exposed infants at three time points: 4 to 12 weeks post-partum to understand early transmission; 12 months post-partum; and 24 months post-partum – after the time of cessation of breastfeeding for most women in Malawi.
NEMAPP is ongoing, comprising 54 randomly selected health facilities from a total of 702 in 10 of 28 districts. A stratified cluster sampling design was used to identify a nationally representative sample of HIV-exposed infants 4 to 26 weeks of age and their mothers. When attending an under-5s clinic, mothers were consented consecutively and screened for HIV. All identified HIV-exposed infants had HIV-1 DNA testing.
Dr Gupta presented unweighted results of early infant transmission at the time of enrolment into NEMAPP. Of the 26,676 mothers screened for HIV, 2641 (9.9%) were enrolled.
Four- to eight-week-old infants accounted for three quarters of the sample. Over 98% of the 1851 HIV-positive mothers of 4- to 12-week-old infants reported knowing their HIV status during pregnancy. Eighty per cent of mothers had access to HIV testing before their last pregnancy. Twenty-five per cent of infants were born to mothers under 25 years of age.
Disclosure between a mother and her partner was high at close to 90% while 70% of partners had told the mother of their status.
A total of 94.5% of mothers reported taking any ART in pregnancy and 97.1% of mothers reported giving their infants nevirapine.
Overall, the vertical transmission rate was 4.1% (n = 73), 95% CI: 3.2-5.2%, p < 0.001.
Under Option B+, vertical transmission of HIV was very low. While mother-to-child transmission among women who were taking ART before pregnancy was extremely low at 1.4% and comparable to rates in developed nations, these findings show that any ART coverage results in a significant reduction in transmission. This includes mothers taking it postpartum (13.3%) or temporarily (8.3%) as in the case of defaulters.
These are the first national outcome results four years after implementation of Option B+ in Malawi. Coverage of HIV-positive mothers was considerably higher than the national average at 79%. There was possible bias, Dr Gupta noted, towards HIV-positive mothers on ART. There are conflicting views of the true ART coverage of this population and Dr Gupta suggested the overall transmission rate may be closer to 5% rather than the 4.1% reported here. Malawi’s impact assessment, due later this year, will clarify this concern, he added.
Validating Malawi’s approach, these findings show the dramatic progress made in preventing mother-to-child transmission within the context of extremely constrained resources in one of the poorest countries in the world. Option B+, following Malawi’s lead, has now been adopted by most countries in sub-Saharan Africa and is recommended as the preferred option by the World Health Organization.
Further analysis of these cohort data is needed, Dr Gupta concluded, as children finish breastfeeding to understand later transmission, retention of their mothers in care and health outcomes, as well as other aspects of preventing transmission.
Tippett Barr B et al. National HIV transmission in 4-12 week olds in Malawi’s PMTCT Option B+ Program, Conference on Retroviruses and Opportunistic Infections, Boston, abstract 35LB, 2016.
