Browsing by Author "Taylor, Stephen"
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- ItemAnti-Group B Streptococcus antibody in infants born to mothers with human immunodeficiency virus (HIV) infection(Elsevier, 2015-01-29) Le Doare, Kirsty; Allen, Lauren; Kampmann, Beate; Heath, Paul Trafford; Taylor, Stephen; Hesseling, Anneke C.; Gorringe, Andrew; Jones, Christine ElizabethBackground: HIV-exposed uninfected infants have increased infection risk and mortality compared to HIV-unexposed infants. HIV-exposed infants may be at increased risk of invasive GBS disease due to reduced maternal antibody against GBS. Methods: We quantified antibodies that bind to the surface of whole Group B Streptococcus (GBS) of serotypes Ia, Ib, II, III and V using novel flow cytometry assays in South African HIV-infected and non-infected mothers and their uninfected infants. Antibody-mediated complement C3b/iC3b deposition onto GBS of these serotypes was also quantified by a novel flow cytometry assay. Results: Geometric mean concentration (GMC) of both surface-binding anti-GBS antibody and antibody-mediated complement deposition onto GBS were reduced in HIV-infected women (n = 46) compared to HIV-uninfected women (n = 58) for ST1a (surface-binding: 19.3 vs 29.3; p = 0.003; complement deposition: 2.9 vs 5.3 SU/mL; p = 0.003), STIb (24.9 vs 47.6; p = 0.003; 2.6 vs 4.9 SU/mL; p = 0.003), STII (19.8 vs 50.0; p = 0.001; 3.1 vs 6.2 SU/mL; p = 0.001), STIII (27.8 vs 60.1; p = 0.001; 2.8 vs 5.3 SU/mL; p = 0.001) and STV (121.9 vs 185.6 SU/mL; p < 0.001) and in their infants for STIa (complement deposition 9.4 vs 27.0 SU/mL; p = 0.02), STIb (13.4 vs 24.5 SU/mL; p = 0.02), STII (14.6 vs 42.7 SU/mL; p = 0.03), STIII (26.6 vs 62.7 SU/mL; p = 0.03) and STV (90.4 vs 165.8 SU/mL; p = 0.04). Median transplacental transfer of antibody from HIV-infected women to their infants was reduced compared to HIV-uninfected women for GBS serotypes II (0.42 [IQR 0.22–0.59] vs 1.0 SU/mL [0.42–1.66]; p < 0.001), III (0.54 [0.31–1.03] vs 0.95 SU/mL [0.42–3.05], p = 0.05) and V (0.51 [0.28–0.79] vs 0.75 SU/mL [0.26–2.9], p = 0.04). The differences between infants remained significant at 16 weeks of age. Conclusions: Maternal HIV infection was associated with lower anti-GBS surface binding antibody concentration and antibody-mediated C3b/iC3b deposition onto GBS bacteria of serotypes Ia, Ib, II, III and V. This may render these infants more susceptible to early and late onset GBS disease.
- ItemEducational outcomes : pathways and performance in South African high schools(Academy of Science of South Africa, 2012-03-14) Reddy, Vijay; Van der Berg, Servaas; Janse van Rensburg, Dean; Taylor, StephenWe analysed the pathways and performances in mathematics of high (secondary) school students in South Africa using a panel-like data set of Grade 8 students who participated in the 2002 Trends in International Mathematics and Science Study (TIMSS) and who were tracked to Grade 12 examination data sets. We examined the relationship between TIMSS mathematics performance and reaching Grade 12, the selection of and performance in Grade 12 mathematics, and success rates in the matriculation examination. The progression of students from schools serving middle-class (Subsystem M) and poorer students (Subsystem P, the majority) was compared. Firstly, mathematics achievement scores in South Africa are low and different performance patterns were shown between the two subsystems. Secondly, students who started with similar Grade 8 mathematics scores had different educational outcomes 4 years later. In Subsystem M schools, Grade 8 mathematics scores were a good indicator of who would pass matric, whilst this relationship was not as strong in Subsystem P schools. Thirdly, there was a stronger association between TIMSS Grade 8 scores and subject choice of matric mathematics in Subsystem M schools than in Subsystem P schools. Fourthly, there was a strong correlation between Grade 8 mathematics performance and matric mathematics achievement. Mathematics performance in the earlier years predicted later mathematics performance. To raise exit level outcomes, mathematics scores need to be raised by Grade 8 or earlier. To improve educational and labour market outcomes, the policy priority should be to build foundational knowledge and skills in numeracy. © 2012. The Authors.
- ItemThe value of large-scale randomised control trials in system-wide improvement : the case of the Reading Catch-Up Programme(Education Association of South Africa, 2017) Fleisch, Brahm; Taylor, Stephen; Schoer, Volker; Mabogoane, ThaboThis article illustrates the value of large-scale impact evaluations with counterfactual components. It begins by exploring the limitations of small-scale impact studies, which do not allow reliable inference to a wider population or which do not use valid comparison groups. The paper then describes the design features of a recent large-scale randomised control trial (RCT) evaluation of an intermediate phase literacy intervention that we evaluated. Using a rigorous sampling process and randomised assignment, the paper shows the value of the approach, and how the RCT method prevents researchers from reaching potentially harmful false positive findings. The paper also considers some of the limitations of the RCT method and makes recommendations to mitigate these.