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.