Introduction Streptococcus pneumoniae (the pneumococcus) is a leading cause of death in under-five children. The HIV/AIDS epidemic in sub-Saharan Africa contributes substantially to the pneumonia burden in the region. Vaccination against pneumococcus is a core component of the pneumococcal disease control program. It is a good, practical and cost-effective option to overcome some of the difficulties in facing the factors which facilitate the occurrence of pneumococcal disease. The aim of this study was to assess the persistence of efficacy of 9-valent pneumococcal conjugate vaccine (PCV9) against radiographically-confirmed pneumonia among children over 24 months of age in comparison to children before 6 months and between 6 and 24 months of age in South Africa. Materials and methods The study was an analytic cohort study using secondary data of a randomised controlled trial (RCT) of PCV9 from the Respiratory and Meningeal Pathogens Research Unit (RMPRU), University of the Witwatersrand. STATA and Epi-info computer software programs were used in the analysis. Findings Three thousand seven hundred PCV9 trial participants, who had chest x-ray records, form the cohort of the study. Overall PCV9 efficacy against radiographically-confirmed pneumonia was 7%. PCV9 was more efficacious against radiographically-confirmed pneumonia in 6 to 24 month of age children (21%) compared to under-6 month (0%) and beyond-24 month of age children (-5%). Partial PCV9 vaccination was more efficacious against radiographically-confirmed pneumonia than full vaccination. The association between partial and complete vaccination and radiographically-confirmed pneumonia was not statistically significant, however. HIV infection profoundly affected the efficacy of PCV9 in all age groups. Other factors which were associated with radiographically-confirmed pneumonia were clinical pneumonia, more than two previous pneumonia admissions and presence of pneumonia predisposing factors. Conclusion and recommendations PCV9 vaccination had limited efficacy against radiographically-confirmed pneumonia. However, it was more effective against radiographically-confirmed pneumonia in 6 to 24 month old children. Partial vaccination was more efficacious than a full course (given at 6, 10 and 14 weeks of age). Adoption of two primary doses of PCV9 with one booster dose, in-depth studies to investigate the factors that affect PCV9 efficacy, raising awareness about the potential effect of these factors on radiographically-confirmed pneumonia and the improvement of HIV/AIDS interventions are recommended.

Diss. (sammanfattning) Stockholm : Karolinska institutet, 2007. / Härtill 4 uppsatser.

Introduction: Despite advances in prevention and treatment of vaccine-preventable diseases, diarrhoeal and pneumococcal diseases remain a major source of morbidity and mortality among children worldwide. The introduction of vaccines has led to dramatic reductions in the burden of infectious diseases and mortality among children. South Africa was the first country in Africa to introduce rotavirus vaccine (RV) and pneumococcal conjugate vaccine (PCV) in 2008 as part of its national immunisation programme. Performance of immunization programmes is commonly measured by the coverage and uptake of vaccines, hence ensuring that every child is immunized at the earliest or appropriate age is an important public health goal. We therefore assessed proportions and factors associated with uptake of RV and PCV among infants who were followed during the routine demographic surveillance system of the Africa Centre Demographic Surveillance Area (DSA) in a rural South Africa setting. Methods: An open cohort of children resident in the DSA aged 12 months or below was prospectively followed between January 2008 and December 2011. Trained interviewers visited households and administered a standardised questionnaire. Mothers and caregivers were asked to show the interviewers the South African Road-To-Health (RTH) card for all children aged 12-23 months at the time of the visit or through maternal recall for children whose RTH card was not available. The RTH card includes dates of all routine vaccinations a child has received. Rotavirus vaccine doses are given at 6 and 14 weeks of age and PCV doses at 6 and 14 weeks and 9 months. Complete uptake was defined as “complete” if a child received all recommended doses of either RV or PCV and incomplete if a child did not receive any dose or received one dose of RV or PCV. Logistic regression models were used to assess factors associated with uptake of RV and PCV separately. Results: A total of 6,263 children were included in the analysis, of which 3,082 (49%) were females. At birth, 3,823 (61%) children were living in rural areas and about one-sixth of the children were living in households located far from a health facility (≥5km). The overall uptake of RV and PCV vaccines among children aged 12 months or below was 50% and 37% respectively. Infants who ever migrated outside the DSA had reduced odds of complete RV and PCV vaccination compared to infants who did not out migrate (adjusted OR=0.49, 95% CI 0.41-0.57) and (adjusted OR=0.52, 95% CI 0.43-0.63) respectively. Complete uptake of RV was associated with the increase in education levels of mothers compared secondary education (adjusted OR=1.70, 95 % CI 1.02-2.34) or tertiary education (adjusted OR=1.80, 95 % CI 0.97-2.44). Infants whose mothers were employed were less likely than infants whose mothers were not employed to have complete vaccination for RV or PCV (adjusted OR=0.71, 95 % CI 0.60-0.84) and (adjusted OR=0.81, 95% CI 0.68-0.96) respectively. Similarly, infants whose mothers were resident in the DSA were more likely than infants whose mothers were not resident to have complete vaccination for RV or PCV (adjusted OR=1.97, 95 % CI 1.49-2.60) and (adjusted OR=1.55, 95% CI 1.16-2.08) respectively. Conclusion and recommendation: The uptake of complete RV and PCV were generally low among children in rural South Africa within our study period. Child outmigration, maternal employment, maternal education and maternal residency in the DSA at child birth were associated with complete uptake of RV and PCV vaccines. Programmes targeting mothers of lower socio-economic status are required. Such programmes may include vaccine awareness and immunization campaigns at the community level to improve vaccine uptake and more targeted interventions in areas with low RV and PCV uptake.