We conclude to the high effectiveness of ZDV+NVPsd, reducing by 72% peripartum MTCT compared to ZDV alone (
3–
6). We cannot demonstrate an additional benefit of adding 3TC to ZDV+NVPsd although starting ZDV+3TC a month earlier than ZDV. It is now internationally recognized that triple drug combinations used together and not sequentially further reduce MTCT, especially for women who need HAART for themselves (
20). However, we identified with ZDV+NVPsd a peripartum regimen that is particularly effective when HAART is not indicated, with comparable results to industrialized countries before the HAART era (
9,
21). The six-week residual risk was independant of the breastfeeding exposure. The prolonged duration of NVP levels in both the mother and the child over the first weeks of life may have reduced early transmission by breastmilk, an added benefit of NVPsd combined with ZDV or ZDV+3TC. Two-year follow-up is under way to estimate the additional postnatal transmission risk and the cumulative effectiveness of our peripartum and postpartum packages (
15).
Comparing directly the different ARV MTCT regimens is difficult. The first African placebo-controlled trials evaluated individual drug regimens (
3,
4,
7,
10). Then, equivalence trials were designed (
8). Three key parameters have varied from trial to trial and impair the direct comparison of published results. The median maternal CD4 count varied between 545/mmm
3 in West Africa ZDV studies (
5) to 370 with ZDV+NVPsd (), 461 in the Uganda NVPsd trial (
7) and 482 in the ZDV+3TC trial (
10). The frequency of cesasrian section was 30% in South Africa (
8), 3–6% in our cohort and exceptionnally elective. We introduced alternatives to prolonged and predominant breastfeeding whereas no neonatal intervention had been proposed in the ZDV reference cohort. Our estimate of the six-week transmission risk includes early postnatal transmission, possibly partly controlled by the neonatal ZDV+NVPsd prophylaxis but impaired by other risk factors, low maternal CD4 and low frequency of cesaerian section. These three factors were controlled for in all analyses. In doing so, our ZDV+NVPsd regimen had the lowest estimate of the residual transmission risk compared to ZDV alone (
3,
4), NVPsd (
7), ZDV+3TC, except its longest regimen with a residual transmission of 5.7% (
10).
The DITRAME PLUS regimens were made of several components, each of them selected based on previous evidence. We did not design the study to investigate their respective contribution as recently done in Thailand in a randomized trial (
22). Indeed, their results strengthen our approach of adding NVPsd to a short-course ZDV regimen. This trial suggests also that the neonatal ZDV+NVPsd prophylaxis has an added value, with a 2.0% residual transmission versus 2.8% in the absence of neonatal NVPsd, although the difference remained below statistical significance (
22). Neonatal NVPsd together with one week of ZDV has recently been shown to prevent more intrapartum transmission than NVPsd in Malawi when no ARV could be given before delivery/birth (
23). This was not the case however when maternal NVPsd had been administered prior to delivery (
24). Based on these evidences, WHO recommends as first line regimen the combination of a short-course of ZDV for pregnant women at ≥28 weeks and children, for at least one week, with NVPsd for both (
20).
We chose a nonrandomized approach to estimate the treatment effect as we considered there was
a priori lack of equipoise between ZDV+NVPsd and ZDV alone. Indeed, ethical principles and time constraints can legitimize the use of nonrandomized designs (
25). The Thai trial conducted at the same time than our study stopped its ZDV alone arm after its first interim analysis as it was already inferior to the two arms evaluating ZDV+NVPsd combinations (
22). We acknowledge that beyond important confounding factors systematically controlled for, e.g. the clinical and immunological stage of HIV disease, the breastfeeding exposure and the duration of the ARV prophylaxis, unconsidered factors could not be taken into account by our design. Of note, the uptake in the cohorts remained constant over time (
26).
Viral resistance has not been a concern with short-course ZDV (
27). In the Uganda NVPsd trial, the resistance mutations were transiently diagnosed in 19% of the mothers but were not associated with transmission (
28,
29). The acquisition of different patterns of transient resistance by 46% of the infected children in this trial was considered due to the neonatal NVPsd rather than to the transmission of resistant virus (
29). Using NVPsd in combination with other drugs, the incidence of viral mutations at six-week postpartum was 15% in industrialized countries (
30). Early results of resistance studies within our cohort confirm that NVP resistance occurs at a high frequency among mothers (33%) and children (23%) despite the use of ZDV+NVPsd instead of NVPsd (
31). Further studies will determine whether resistance to 3TC has been added to resistance to NVPsd (
11,
32) and conversely, if the three-day maternal postpartum ZDV+3TC regimen has influenced or not the occurrence of maternal NVP resistance (
33). The consequences of viral resistance after NVPsd exposure on the subsequent response to HAART in women and children should be urgently investigated in Africa like in the Thai trial (
34) considering the possible large-scale adverse effect on subsequent treatment options.
The ZDV+3TC+NVPsd regimen we evaluated was selected at a time access to HAART was too limited in Côte d’lvoire to be considered during pregnancy. Our choice was based on the demonstrated efficacy of short-courses of ZDV+3TC in the ANRS 075 cohort in France (
11) and in the PETRA trial in Africa (
10). We did not demonstrate an enhanced effectiveness of this regimen compared to ZDV+NVPsd, although our study had limited statistical power, an uneven distribution of confounding variables between the two groups (controlled for in the analysis) and was terminated mid-2003 as soon as HAART became available on site.
The ZDV+NVPsd MTCT prophylactic regimen we evaluated is now part of the list of internationally recommended drug regimens by WHO (
20). Once the benefit (effectiveness)/risk (resistance) ratio of the ZDV+3TC+NVPsd combination is known, this regimen may also be considered. Four areas now require further research consideration. First, the uptake of ARV peripartum interventions is critical to obtain a public health impact. ZDV and NVPsd are not easy to use in Africa (
35–
37). Their combined use will not be necessarily more complex but the challenge is to improve coverage (
26). Second, the reduction of the risk of postnatal transmission should be adressed, either with infant feeding strategies (
15) or with ARV-based approaches (
38). Third, alternatives to NVPsd containing regimens should be investigated as viral resistance and impaired response to subsequent ARV treatment is a serious concern. Finally, the residual transmission we observed with ZDV+NVPsd cannot be considered fully satisfactory. HAART is now universally recommended for pregnant women who fulfill this indication for themselves (
20). We demonstrate in a large African cohort, like in a randomized trial in Thailand, that a short-course peripartum ZDV regimen combined with NVPsd is more effective than previously used single drug regimens and will greatly contribute to the prevention of paediatric HIV infection if rapidly and widely used.