Menu
Menu
Menu
Menu
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.
We conducted a cross–sectional clinic-based survey assessing uptake of ART among HIV infected mothers and MTCT prevalence among their HIV exposed infants 4–12 weeks of age. We recruited caregivers (hereafter referred to as mothers) and their infants from those seeking routine immunization or postnatal care services in 60 selected public health facilities between August 2014 and February 2015. We used a two-stage sampling method to recruit participants for this study. The sampling frame for the primary sampling unit was composed of public health facilities offering routine primary health care services to mothers and children throughout Namibia. We stratified all 326 public health facilities providing routine vaccination into five strata based on quintiles of the number of first doses of DPT vaccine administered during 2012, which was used as a measure of size of the number of infants that received care at each facility. Due to the feasibility and logistics of recruiting participants from the least visited clinics in the first quintile, we excluded this stratum from our sampling frame. This stratum contained 67 clinics, which accounted for 1.4% (841/62,088) of first doses of DPT vaccine administered across all clinics. In the first stage of sampling, within each of the four remaining sampling strata we randomly selected 15 health facilities, for a total of 60 facilities (23% of all eligible facilities). The selected facilities covered all 13 regions in Namibia. In the second stage, we recruited and enrolled all eligible and consenting caregiver-infant pairs in each facility for 19 consecutive weeks. The sampling weight for each caregiver-infant pair was calculated as the inverse of the probability of selection, defined as the probability of selecting the health facility in the first stage multiplied by the probability of selecting an HIV-exposed infant with test results in the selected health facility in the second stage. The second stage probability was based on the number of first doses of DPT vaccine administered during 2014 to reflect the total population of infants receiving care at all of the facilities at the time of sampling. HIV-exposed infants age 4–12 weeks were identified by maternal HIV infection status. We included women with a documented HIV positive status on either the ANC card or health passport and identified new positives by testing all women with a previous negative or unknown status per national testing guidelines. We excluded severely ill infants, infants whose mothers refused consent and those younger than 4 weeks or older than 12 weeks. We trained nurses at site level to identify all potentially eligible mother-infant pairs and work with trained data collectors to complete a standardized screening and interview questionnaire. We screened mother-infant pairs in two steps: (1) ensure the child was not brought to the health facility for emergency medical care and the child had not already been enrolled in the study, and (2) include only infants aged 4–12 weeks and mothers who consented for the study. For those who met these inclusion criteria, and provided written consent to participate in the study, we used the standardized questionnaire to gather sociodemographic data, clinical, treatment, and feeding data from the mother-infant pair. In addition to interviewing the mother, some clinical information was extracted from the maternal ANC cards and the infant child health passports (maternal HIV status, maternal ART use, infant HIV exposure status, and infant ARV prophylaxis). Study nurses recorded infant HIV PCR tests and results in routine MOHSS clinic registers at each site. Confidential participant identification numbers were recorded in the study register(s) for infants/mothers enrolled in the study. The participant identification number was placed on the dried blood spot card, the laboratory request form, and the questionnaire. All interview data and laboratory results were collected on password protected smartphones and uploaded daily to a secure central database. The clinic healthcare providers conducted pre- and post-test counselling and delivered HIV test results to the mother-infant pairs as per standard clinic procedures. Mothers with an unknown or previous HIV negative status were tested using parallel HIV rapid tests. Discordant results between two rapid tests were confirmed by a third rapid test (tiebreaker). All rapid HIV tests were done at the study health facilities by trained health workers. Trained nurses collected blood samples from HIV exposed-infants whose mothers consented for infant’s HIV test on a 5-spot Guthrie card as dried blood spots. All dried blood spot specimens accompanied by routine laboratory request forms were sent to the central laboratory for HIV DNA PCR testing using COBAS AmpliPrep/COBAS TaqMan HIV-1 Qualitative Test version 2.0. Infant’s dried blood spot DNA PCR HIV test results were returned to the mother within 2–4 weeks of testing. Prior to participation, eligible mothers were read an information sheet including study procedures and confidentiality and asked to sign written informed consent prior to participation. The participant identification numbers were used to link the mother’s and infant’s information and to provide the infant’s HIV test results to be used for clinical care. The participant identification number, name, phone number, home address and direction to home that were collected with the mother’s consent were kept in a locked box at the facility only accessed by the facility nurse and data collector. HIV test results were returned to the mother or legal guardian by clinic nurses who complied with the national guidelines. All data collectors and supervisors were trained on confidentiality procedures and signed a confidentiality agreement. All electronic survey data were encrypted. The study was approved by Namibia’s Ministry of Health and Social Services research ethical committees. The study was also reviewed in accordance with CDC human research protection procedures and was determined to be research, but CDC investigators did not interact with human subjects or have access to identifiable data or specimens for research purposes. We calculated descriptive statistics for maternal and infant characteristics. We calculated the weighted estimate of the national prevalence of early MTCT at 4–12 weeks and 95% confidence interval (CI). To determine importance of timing of maternal ART, we categorized self-reported maternal ART into four groups of maternal ART initiation timing: before pregnancy, during pregnancy (including delivery), after delivery, or mother never received ART. To assess additional benefit of infant prophylaxis, we also created a composite factor for maternal ART and infant ARV prophylaxis: mother received ART and infant received ARV prophylaxis, mother received ART but infant did not receive ARV prophylaxis, mother did not receive ART and infant received ARV prophylaxis, or neither received ART/ARV. For categories of each maternal and infant characteristic, we estimated the prevalence of MTCT and 95% CI. To evaluate the association between each maternal/infant characteristic and/or PMTCT intervention and the ultimate outcome-infant HIV infection, we performed the design-based Pearson’s chi-square test. For evaluating each association, we fit a Poisson regression model to calculate prevalence ratios and 95% CIs [13]. Characteristics with a p-value less than 0.20 were considered for a multivariable Poisson regression model. Statistical significance was assessed at the 0.05 level for all analyses. All analyses were performed using Stata software version 14.2 and accounted for the two-stage survey design and sampling weights (svyset command).
N/A
