Commentary: Challenging public health orthodoxies--prophesy or heresy?

The emergence and current performance of a health research system: lessons from Guinea Bissau

BACKGROUND

Little is known about how health research systems (HRS) in low-income countries emerge and evolve over time, and how this process relates to their performance. Understanding how HRSs emerge is important for the development of well functioning National Health Research Systems (NHRS). The aim of this study was to assess how the HRS in Guinea Bissau has emerged and evolved over time and how the present system functions.

METHODS

We used a qualitative case-study methodology to explore the emergence and current performance of the HRS, using the NHRS framework. We reviewed documents and carried out 39 in-depth interviews, ranging from health research to policy and practice stakeholders. Using an iterative approach, we undertook a thematic analysis of the data.

RESULTS

The research practices in Guinea Bissau led to the emergence of a HRS with both local and international links and strong dependencies on international partners and donors. The post-colonial, volatile and resource-dependent context, changes in donor policies, training of local researchers and nature of the research findings influenced how the HRS evolved. Research priorities have mostly been set by 'expatriate' researchers and focused on understanding and reducing child mortality. Research funding is almost exclusively provided by foreign donors and international agencies. The training of Guinean researchers started in the mid-nineties and has since reinforced the links with the health system, broadened the research agenda and enhanced local use of research. While some studies have made an important contribution to global health, the use of research within Guinea Bissau has been constrained by the weak and donor dependent health system, volatile government, top-down policies of international agencies, and the controversial nature of some of the research findings.

CONCLUSIONS

In Guinea Bissau a de facto 'system' of research has emerged through research practices and co-evolving national and international research and development dynamics. If the aim of research is to contribute to local decision making, it is essential to modulate the emerged system by setting national research priorities, aligning funding, building national research capacity and linking research to decision making processes. Donors and international agencies can contribute to this process by coordinating their efforts and aligning to national priorities.

Vaccination status and sequence of vaccinations as risk factors for hospitalisation among outpatients in a high mortality country

BACKGROUND

Most developing countries are implementing the WHO immunisation programme. Although vaccines reach most children, many modifications of the recommended schedule are observed in practice. We investigated the association between vaccination status and risk of hospitalisation in Guinea-Bissau.

METHODS

From May 2003 to May 2004, all consultations of children less than five years of age at the outpatient clinic of the paediatric ward at the national hospital in Bissau were registered. For each consultation, information was collected about the child's name, sex, age and socio-cultural conditions, as well as diagnosis and whether the child was hospitalised. Information about vaccinations was also registered from the child's vaccination card. We analysed the association between vaccination status and risk of hospitalisation in age intervals according to the pre-dominant vaccines. We particularly emphasised the comparison of those who had received the recommended vaccination for the age groups and those who were delayed and only had the previous vaccinations. We also examined those who had received the vaccines out of sequence.

RESULTS

Information about vaccinations was available for 11,949 outpatient children of whom 2219 (19%) were hospitalised. Among children less than 3 months of age, unvaccinated children compared to BCG children had as expected a higher risk of hospitalisation; controlled for important determinants of hospitalisation, the hospitalisation risk ratio (HRR) was 1.99 (95% CI 1.37-2.89). In contrast, there was no difference in the HRR for children aged 1½-8 months who were delayed and had only received BCG compared to those who as recommended had received diphtheria-tetanus-pertussis (DTP) vaccine after BCG (HRR=1.10 (0.77-1.59)). In the age interval 9-17 months of age, children who were delayed and had only received DTP had significantly higher risk of hospitalisation compared with children who as recommended had measles vaccine (MV) as the most recent vaccination (HRR=1.39 (1.16-1.66)). Having received DTP after MV (HRR=1.60 (1.15-2.24)) or MV and DTP simultaneously (HRR=1.51 (1.16-1.97)) was also associated with higher risk than MV only as most recent vaccination. In contrast, the children aged 18-59 months who as recommended had received a DTP booster after MV did not have lower risk of hospitalisations compared with children who were delayed and had received only MV (RR=0.90 (0.75-1.07)). After 9 months of age, there was a significant difference in the female-male HRR for children who had MV (HRR=0.85 (0.72-1.00)) or DTP (HRR=1.08 (0.96-1.22)) as most recent vaccination (p=0.02, test of interaction).

CONCLUSION

Following the recommended vaccination schedule for BCG and MV is associated with a reduced risk of hospitalisation but this is not the case for DTP and booster DTP. Receiving DTP simultaneously with MV or after MV is associated with increased risk of hospitalisation. Vaccines have sex-differential effects on the risk of hospitalisation.

Sex differences in the effect of vaccines on the risk of hospitalization due to measles in Guinea-bissau

BACKGROUND

Routine immunizations have non-specific and sex-differential effects on childhood mortality and morbidity in low-income countries; BCG and measles vaccine (MV) may reduce and diphtheria-tetanus-pertussis vaccine (DTP) may increase the mortality of girls relative to boys.

SETTING

Urban area in Guinea-Bissau, with a demographic surveillance system and registration of all pediatric hospitalizations. Guinea-Bissau experienced a large outbreak of measles infection in 2003-2004.

DESIGN

We used hospital and community data to examine the impact of other vaccines on the risk of hospitalizations for measles infection. Vaccine efficacy (VE) against hospitalization for children aged 6 to 59 months of age was examined. We assessed whether VE depended on vaccination status for other vaccines and whether the pattern differed for boys and girls.

MAIN OUTCOME MEASURE

Sex-specific vaccine efficacy against hospitalization for children aged 6 to 59 months of age.

RESULTS

The VE depended on sex and the sequence of vaccinations. The VE of MV against hospitalization for measles was better for girls than for boys. Among children who had received MV as the most recent vaccine VE against hospitalization was as high as 96% for girls, but only 81% for boys (P = 0.002). Among children who had received DTP simultaneously with MV or DTP after MV, VE declined for girls (91%) and increased for boys (90%). Compared with having received MV as most recent vaccination, DTP simultaneously with MV or DTP after MV improved the efficacy significantly for boys and the effect was significantly different for boys and girls (P = 0.023). The female-male risk ratio of hospitalization varied significantly, depending on the most recent vaccination (P = 0.014); it was 0.28 (0.11-0.68) for MV alone, but 1.21 (0.82-1.77) for DTP but no MV, and 1.13 (0.58-2.18) for DTP simultaneously with MV or after MV. Among MV-unvaccinated children, BCG-vaccinated girls had a lower risk of measles hospitalization than DTP-vaccinated girls (RR=0.0 (0.0-0.99), exact test).

Landscape analysis of interactions between nutrition and vaccine responses in children

The world's poorest children are likely to be malnourished when receiving their childhood vaccines. It is uncertain whether this affects vaccine efficacy and whether the coadministration of nutrient supplements with vaccines has beneficial or detrimental effects. More recently, a detrimental interaction between vitamin A (VA) supplementation (VAS) and the killed diphtheria-tetanus-pertussis vaccine given in early childhood has been suggested. This report provides a critical review of the published interactions between nutritional status and/or supplementation and vaccine responses in children. Due to an absence of evidence for most nutrients, this analysis focused on protein-energy, vitamins A and D, and iron and zinc. All vaccines were considered. Both observational studies and clinical trials that led to peer-reviewed publications in English or French were included. These criteria led to a pool of 58 studies for protein-energy malnutrition, 43 for VA, 4 for vitamin D, 10 for iron, and 22 for zinc. Our analysis indicates that malnutrition has surprisingly little or no effect on vaccine responses. Evidence for definitive adjunctive effects of micronutrient supplementation at the time of vaccination is also weak. Overall, the paucity, poor quality, and heterogeneity of data make it difficult to draw firm conclusions. The use of simple endpoints that may not correlate strongly with disease protection adds uncertainty. A detailed examination of the immunological mechanisms involved in potential interactions, employing modern methodologies, is therefore required. This would also help us understand the proposed, but still unproven, negative interactions between VAS and vaccine safety, a resolution of which is urgently required.