Very low transmission rates among breastfeeding women receiving ART

3 September 2007. Related: Conference reports, Pregnancy, IAS 4th Sydney 2007.

Polly Clayden, HIV i-Base

Two oral presentations reported very low rates of transmission among breastfeeding women receiving ART (both indicated and not indicated for treatment for their own health). These interim results looked very promising.

Charles Kilewo from the Muhimbili University College of Health Sciences, in Dar es Salaam, Tanzania, presented findings from MITRA PLUS, which is an open-label, non-randomised, prospective study to evaluate the impact of maternal ART on mother-to-child transmission during pregnancy and breastfeeding.

In this study the mothers received AZT + 3TC + NVP during late pregnancy and breastfeeding (NVP was later replaced by nelfinavir for mothers CD4 counts above 250 cells/mm3). ART was initiated at 34 weeks of pregnancy or earlier if the woman presented with CD4 cell counts below 200 cells/mm3 or were otherwise indicated for treatment. The infants received AZT + 3TC for one week after birth.

Mothers stopped treatment at six months except where indicated for their own health. Mothers were counselled to exclusively breastfeed and encouraged to stop at six months. The median time of breastfeeding was 24 weeks.

441 infants were included in the survival analysis. The cumulative proportion of HIV-positive infants was 4.1 % (95% CI 2.1%-6.0%) at 6 weeks and 5.0% (95% CI: 3.2-7.0%) at 6 months.

The investigators concluded: “The strategy can be adopted by women in developing countries who intend to breast-feed their infants and has the advantage that mothers with low CD4 cell counts will benefit from the treatment for their own health.”

In the following presentation Vic Arendt of the Centre Hospitalier de Luxembourg, with the Centre Hospitalier Universitaire de Kigali, presented findings from AMATA, a study conducted at four antenatal sites in Kigali, Rwanda, which compared transmission risk between breastfeeding and formula feeding mothers receiving ART.

In this study, women with CD4 <350 cells/mm3 received NVP+3TC+d4T and chose between breast and formula feeding. Women with CD4 >350 cells/mm3 (clinical stage 1,2 and 3) received AZT+3TC+EFV from 26 weeks and chose between breast and formula feeding. Women who chose formula feeding stopped ART at delivery. Breastfeeding women stopped ART at 7 months (both groups with 7 days 3TC+AZT “tail” coverage). Infants received single dose NVP+7 days AZT.

Dr Arendt reported 573 women were enrolled in this study. 557 had delivered as of July, 2007. 316 mothers (57%) opted to formula feed while 238 (43%) chose breastfeeding. PCR results were available for 484 (90%) infants at 6 weeks and for 431 (87%) at 7 months of age (255 formula and 176 breastfed).

52% mothers had viral load at delivery <40 copies/mL; 38% 40-1000 copies/mL and 10% >1000 copies/mL.

So far 7/431 (1.6%) infants are HIV-positive; 6 were infected at birth. 1/176 (0.6%) infant was infected through breastfeeding (CI: 0.3-100). The mother’s viral load was <40 copies/mm3 at delivery and 3.6 log at weaning so it is possible that she was non-adherent.

The investigators found no significant difference in weight or growth between infants in the two feeding groups.

There was no significant difference in morbidity, with 1.32 disease episodes during the first 6 months in formula fed infants compared to 1.23 episodes in breastfed infants (p=0.26). Nor was the difference in mortality significant: 18 (6%) formula fed infants died, compared to 6 (3%) breastfed infants (p=0.15).

The investigators concluded that low transmission rates are achievable using ART pre and post partum. “Breastfeeding among ART-treated mothers is associated with low transmission rate while maintaining the benefits of breastfeeding.” They noted that there was no difference in morbidity, mortality and development in children formula fed or breastfed.

Comment

This has been one of the big questions, and these results suggest that potentially the benefits breastfeeding could be preserved without transmission risk by treating mothers. In these studies, <1% and 1.6% transmissions are attributed to breastfeeding. In the first study though, the women were largely healthy – 93.9% stage 1. In the second study – if formula feeding is so stigmatised, how come 57% opted to do so?

Despite the apocalyptic scenarios predicted for formula fed babies, there were no significant differences in morbidity and mortality but with 18 vs 6 (p=0.15) investigators suggested a trend.

References:

1. Kilewo C, Karlsson K, Ngarina M et al. Prevention of mother to child transmission of HIV-1 through breastfeeding by treating mothers prophylactically with triple antiretroviral therapy in Dar es Salaam, Tanzania – the MITRA Plus study. 4th IAS conference, Sydney, 2007. Oral abstract TUAX101.
2. Arendt V, Ndimubanzi P, Vyankandondera J et al. AMATA study: effectiveness of antiretroviral therapy in breastfeeding mothers to prevent post-natal vertical transmission in Rwanda. 4th IAS conference, Sydney, 2007. Oral abstract TUAX102.