Data from: National-level effectiveness of ART to prevent early mother to child transmission of HIV in Namibia

Background: Namibia introduced the prevention of mother to child HIV transmission (MTCT) program in 2002 and lifelong antiretroviral therapy (ART) for pregnant women (option B-plus) in 2013. We sought to quantify MTCT measured at 4-12 weeks post-delivery. Methods: During Aug 2014-Feb 2015, we recruited a nationally representative sample of 1040 pairs of mother and infant aged 4-12 weeks at routine immunizations in 60 public health clinics using two stage sampling approach. Of these, 864 HIV exposed infants had DNA-PCR HIV test results available. We defined an HIV exposed infant if born to an HIV-positive mother with documented status or diagnosed at enrollment using rapid HIV tests. Dried Blood Spots samples from HIV exposed infants were tested for HIV. Interview data and laboratory results were collected on smartphones and uploaded to a central database. We measured MTCT prevalence at 4-12 weeks post-delivery and evaluated associations between infant HIV infection and maternal and infant characteristics including maternal treatment and infant prophylaxis. All statistical analyses accounted for the survey design. Results: Based on the 864 HIV exposed infants with test results available, nationally weighted early MTCT measured at 4-12 weeks post-delivery was 1.74% (95% confidence interval (CI): 1.00%-3.01%). Overall, 62% of mothers started ART pre-conception, 33.6% during pregnancy, 1.2% post-delivery and 3.2% never received ART. Mothers who started ART before pregnancy and during pregnancy had low MTCT prevalence, 0.78% (95% CI: 0.31%-1.96%) and 0.98% (95% CI: 0.33%-2.91%), respectively. MTCT rose to 4.13% (95% CI: 0.54%-25.68%) when the mother started ART after delivery and to 11.62% (95% CI: 4.07%-28.96%) when she never received ART. The lowest MTCT of 0.76% (95% CI: 0.36% - 1.61%) was achieved when mother received ART and ARV prophylaxis within 72hrs for infant and highest 22.32% (95%CI: 2.78% -74.25%) when neither mother nor infant received ARVs. After adjusting for mother's age, maternal ART (Prevalence Ratio (PR)=0.10, 95% CI: 0.03 – 0.29) and infant ARV prophylaxis (PR=0.32, 95% CI: 0.10 – 0.998) remained strong predictors of HIV transmission. Conclusion: As of 2015, Namibia achieved MTCT of 1.74%, measured at 4-12 weeks post-delivery. Women already on ART pre-conception had the lowest prevalence of MTCT emphasizing the importance of early HIV diagnosis and treatment initiation before pregnancy. Studies are needed to measure MTCT and maternal HIV seroconversion during breastfeeding.背景：纳米比亚于2002年启动艾滋病母婴传播（Mother-to-Child HIV Transmission, MTCT）预防项目，并于2013年为孕妇推出终身抗逆转录病毒治疗（Antiretroviral Therapy, ART）B+方案。本研究旨在量化分娩后4~12周检测的艾滋病母婴传播率。方法：2014年8月至2015年2月，本研究采用两阶段抽样方法，在60所公立卫生机构的常规免疫接种现场，招募了1040对分娩后4~12周的母婴作为全国代表性样本。其中，864名艾滋病暴露婴儿拥有DNA聚合酶链反应（Deoxyribonucleic Acid-Polymerase Chain Reaction, DNA-PCR）HIV检测结果。本研究将艾滋病暴露婴儿定义为：母亲为HIV阳性且有感染记录，或入组时经快速HIV检测确诊的婴儿。研究人员对艾滋病暴露婴儿的干血斑（Dried Blood Spots, DBS）样本进行HIV检测。通过智能手机收集访谈数据与实验室检测结果，并上传至中央数据库。本研究测定了分娩后4~12周的艾滋病母婴传播率，并分析婴儿HIV感染与母婴特征（包括母亲抗病毒治疗情况与婴儿预防用药情况）之间的关联。所有统计分析均考虑了抽样设计的影响。结果：基于864名拥有检测结果的艾滋病暴露婴儿，经全国加权后的分娩后4~12周早期艾滋病母婴传播率为1.74%（95%置信区间（Confidence Interval, CI）：1.00%~3.01%）。总体而言，62%的母亲在孕前启动抗逆转录病毒治疗，33.6%在孕期启动，1.2%在产后启动，另有3.2%的母亲从未接受过抗逆转录病毒治疗。孕前及孕期启动抗逆转录病毒治疗的母亲，其婴儿的艾滋病母婴传播率较低，分别为0.78%（95% CI：0.31%~1.96%）与0.98%（95% CI：0.33%~2.91%）。母亲在产后启动抗逆转录病毒治疗时，婴儿的艾滋病母婴传播率升至4.13%（95% CI：0.54%~25.68%）；母亲从未接受抗逆转录病毒治疗时，该率升至11.62%（95% CI：4.07%~28.96%）。当母亲接受抗逆转录病毒治疗且婴儿在72小时内接受抗逆转录病毒预防用药时，艾滋病母婴传播率最低，为0.76%（95% CI：0.36%~1.61%）；当母亲与婴儿均未接受抗逆转录病毒药物时，该率最高，达22.32%（95% CI：2.78%~74.25%）。在校正母亲年龄后，母亲抗逆转录病毒治疗（患病率比（Prevalence Ratio, PR）=0.10，95% CI：0.03~0.29）与婴儿抗逆转录病毒预防用药（PR=0.32，95% CI：0.10~0.998）仍是HIV传播的强预测因子。结论：截至2015年，纳米比亚分娩后4~12周检测的艾滋病母婴传播率为1.74%。孕前已接受抗逆转录病毒治疗的女性，其婴儿的艾滋病母婴传播率最低，这凸显了孕前早期HIV诊断与启动治疗的重要性。未来仍需开展研究，以评估母乳喂养期间的艾滋病母婴传播率及母亲的HIV血清阳转情况。