A Preliminary Assessment of Rotavirus Vaccine Effectiveness in Zambia.

BACKGROUND: Diarrhea is the third leading cause of child death in Zambia. Up to one-third of diarrhea cases resulting in hospitalization and/or death are caused by vaccine-preventable rotavirus. In January 2012, Zambia initiated a pilot introduction of the Rotarix live, oral rotavirus vaccine in all public health facilities in Lusaka Province. METHODS: Between July 2012 and October 2013, we conducted a case-control study at 6 public sector sites to estimate rotavirus vaccine effectiveness (VE) in age-eligible children presenting with diarrhea. We computed the odds of having received at least 1 dose of Rotarix among children whose stool was positive for rotavirus antigen (cases) and children whose stool was negative (controls). We adjusted the resulting odds ratio (OR) for patient age, calendar month of presentation, and clinical site, and expressed VE as (1 - adjusted OR) × 100. RESULTS: A total of 91 rotavirus-positive cases and 298 rotavirus-negative controls who had under-5 card-confirmed vaccination status and were ≥6 months of age were included in the case-control analysis. Among rotavirus-positive children who were age-eligible to be vaccinated, 20% were hospitalized. Against rotavirus diarrhea of all severity, the adjusted 2-dose VE was 26% (95% confidence interval [CI], -30% to 58%) among children ≥6 months of age. VE against hospitalized children ≥6 months of age was 56% (95% CI, -34% to 86%). CONCLUSIONS: We observed a higher point estimate for VE against increased severity of illness compared with milder disease, but were not powered to detect a low level of VE against milder disease.

Field performance evaluation of dual rapid HIV and syphilis tests in three antenatal care clinics in Zambia.

This cross-sectional study of 3212 pregnant women assessed the field performance, acceptability, and feasibility of two dual HIV/syphilis rapid diagnostic tests, the Chembio DPP HIV-syphilis Assay and the SD Bioline HIV/syphilis Duo in antenatal clinics. Sensitivity and specificity for HIV and syphilis were calculated compared to the rapid Determine HIV-1/2 with Uni-Gold to confirm positive results for HIV and the Treponema pallidum particle agglutination assay for syphilis. RPR titers ≥1:4 were used to define active syphilis detection. Acceptability and feasibility were assessed using self-reported questionnaires. For Chembio, the HIV sensitivity was 90.6% (95%CI = 87.4, 93.0) and specificity was 97.2% (95%CI = 96.2, 97.8); syphilis sensitivity was 68.6% (95%CI = 61.9, 74.6) and specificity was 98.5% (95%CI = 97.8, 98.9). For SD Bioline, HIV sensitivity was 89.4% (95%CI = 86.1, 92.0) and specificity was 96.3% (95%CI = 95.3, 97.1); syphilis sensitivity was 66.2% (95%CI = 59.4, 72.4) and specificity was 97.2% (95%CI = 96.4, 97.9). Using the reference for active syphilis, syphilis sensitivity was 84.7% (95%CI = 76.1, 90.6) for Chembio and 81.6% (95%CI = 72.7, 88.1) for SD Bioline. Both rapid diagnostic tests were assessed as highly acceptable and feasible. In a field setting, the performance of both rapid diagnostic tests was comparable to other published field evaluations and each was rated highly acceptable and feasible. These findings can be used to guide further research and proposed scale up in antenatal clinic settings.