Use of Vaccine Trials to Estimate Burden of Disease

Vaccine trials, the most informative way of determining the efficacy of a vaccine, can also provide valuable information about the burden of disease. The burden of Haemophilus influenzae type b (Hib)remains a major barrier to the use of Hib vaccines, especially in Asia. Recent studies in Indonesia and Bangladesh have used vaccine-trial designs, with known effective vaccines, to estimate the vaccinepreventable burden of Hib disease in those communities. New vaccines against pneumonia and diarrhoeal diseases are usually directed at only one of various causes of the syndrome. In the case of pneumonia, it is very difficult to determine the aetiology in most cases, so the vaccine trial offers a means of determining the burden of vaccine-preventable diseases. This is particularly important for pneumococcal vaccines as serotype replacement may reduce the effectiveness of the vaccines in the field. This approach would underestimate disease burden if vaccines were found to have an impact on syndromes other than those against which they are directed, and might lead to errors in estimation if there were erroneous assumptions about the efficacy of the vaccine against the condition under investigation

Beyond good intentions: lessons on equipment donation from an African hospital.

OBJECTIVE: In 2000, a referral hospital in the Gambia accepted a donation of oxygen concentrators to help maintain oxygen supplies. The concentrators broke down and were put into storage. A case study was done to find the reasons for the problem and to draw lessons to help improve both oxygen supplies and the success of future equipment donations. METHODS: A technical assessment of the concentrators was carried out by a biomedical engineer with relevant expertise. Semi-structured interviews were undertaken with key informants, and content analysis and inductive approaches were applied to construct the history of the episode and the reasons for the failure. FINDINGS: Interviews confirmed the importance of technical problems with the equipment. They also revealed that the donation process was flawed, and that the hospital did not have the expertise to assess or maintain the equipment. Technical assessment showed that all units had the wrong voltage and frequency, leading to overheating and breakdown. Subsequently a hospital donations committee was established to oversee the donations process. On-site biomedical engineering expertise was arranged with a nongovernmental organization (NGO) partner. CONCLUSION: Appropriate donations of medical equipment, including oxygen concentrators, can be of benefit to hospitals in resource-poor settings, but recipients and donors need to actively manage donations to ensure that the donations are beneficial. Success requires planning, technical expertise and local participation. Partners with relevant skills and resources may also be needed. In 2002, WHO produced guidelines for medical equipment donations, which address problems that might be encountered. These guidelines should be publicized and used

State-of-the-art in the pneumococcal field: Proceedings of the 11th International Symposium on Pneumococci and Pneumococcal Diseases (ISPPD-11).

The International Symposium on Pneumococci and Pneumococcal Diseases (ISPPD) is the premier global scientific symposium dedicated to the exchange, advancement and dissemination of the latest research on the pneumococcus, one of the world's deadliest bacterial pathogens. Since the first ISPPD was held in 1998, substantial progress has been made to control pneumococcal disease, for instance, more than half of surviving infants (78.6 million) from 143 countries now have access to the life-saving pneumococcal conjugate vaccine (PCV). The 11th ISPPD (ISPPD-11) was held in Melbourne, Australia in April 2018 and the proceedings of the symposium are captured in this report. Twenty years on from the first ISPPD, there remain many challenges and unanswered questions such as the continued disparity in disease incidence in Indigenous populations, the slow roll-out of PCV in some regions such as Asia, the persisting burden of disease in adults, serotype replacement and diagnosis of pneumococcal pneumonia. ISPPD-11 also put the spotlight on cutting-edge science including metagenomic, transcriptomic, microscopy, medical imaging and mathematical modelling approaches. ISPPD-11 was highly diverse, bringing together 1184 delegates from 86 countries, representing various fields including academia, primary healthcare, pharmaceuticals, biotechnology, policymakers and public health

Preventive measures in infancy to reduce under-five mortality: a case-control study in The Gambia.

OBJECTIVE: To investigate the relationship between child mortality and common preventive interventions: vaccination, trained birthing attendants, tetanus toxoid during pregnancy, breastfeeding and vitamin A supplementation. METHODS: Case-control study in a population under demographic surveillance. Cases (n = 141) were children under five who died. Each was age and sex-matched to five controls (n = 705). Information was gathered by interviewing primary caregivers. RESULTS: All but one of the interventions - whether the mother had received tetanus toxoid during pregnancy - were protective against child mortality after multivariate analysis. Having a trained person assisting at child birth (OR 0.2 95% CI 0.1-0.4), receiving all vaccinations by 9 months of age (OR 0.1; 95% CI 0.01-0.3), being breastfed for more than 12 months (Children breastfed between 13 and 24 months OR 0.1 95% CI 0.03-0.3, more than 25 months OR 0.1 95% CI 0.01-0.5) and receiving vitamin A supplementation at or after 6 months of age (OR 0.05; 95% CI 0.01-0.2) were protective against child death. CONCLUSIONS: This study confirms the value of at least four available interventions in the prevention of under-five death in The Gambia. It is now important to identify those who are not receiving them and why, and to intervene to improve coverage across the population

Long-term impact of pneumococcal polysaccharide vaccination on nasopharyngeal carriage in children previously vaccinated with various pneumococcal conjugate vaccine regimes

Previously, the Fiji Pneumococcal Project (FiPP) evaluated reduced dose immunization schedules that incorporated pneumococcal protein conjugate and/or polysaccharide vaccine (PCV7 and 23vPPV, respectively). Immune hyporesponsiveness was observed in children vaccinated with 23vPPV at 12 months of age compared with children who did not receive 23vPPV.Here we assess the long-term impact of 23vPPV vaccination on nasopharyngeal carriage rates and densities of Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus and Moraxella catarrhalis. Nasopharyngeal swabs (n = 194) were obtained from healthy children who participated in FiPP (now aged 5–7 years). S. pneumoniae were isolated and identified by standard culture-based methods, and serotyped using latex agglutination and the Quellung reaction. Carriage rates and densities of S. pneumoniae, H. influenzae, S. aureus and M. catarrhalis were determined using real-time quantitative PCR.There were no differences in the rate or density of S. pneumoniae, H. influenzae or M. catarrhalis carriage by PCV7 dose or 23vPPV vaccination in the vaccinated participants overall. However, differences were observed between the two main ethnic groups: Fijian children of Indian descent (Indo-Fijian) were less likely to carry S. pneumoniae, H. influenzae and M. catarrhalis, and there was evidence of a higher carriage rate of S. aureus compared with indigenous Fijian (iTaukei) children. Polysaccharide vaccination appeared to have effects that varied between ethnic groups, with 23vPPV vaccination associated with a higher carriage rate of S. aureus in iTaukei children, while there was a lower carriage rate of S. pneumoniae associated with 23vPPV vaccination in Indo-Fijian children.Overall, polysaccharide vaccination had no long-term impact on pneumococcal carriage, but may have impacted on S. aureus carriage and have varying effects in ethnic groups, suggesting current WHO vaccine schedule recommendations against the use of 23vPPV in children under two years of age are appropriate

Asymmetric Fluid Criticality I: Scaling with Pressure Mixing

The thermodynamic behavior of a fluid near a vapor-liquid and, hence, asymmetric critical point is discussed within a general ``complete'' scaling theory incorporating pressure mixing in the nonlinear scaling fields as well as corrections to scaling. This theory allows for a Yang-Yang anomaly in which \mu_{\sigma}^{\prime\prime}(T), the second temperature derivative of the chemical potential along the phase boundary, diverges like the specific heat when T\to T_{\scriptsize c}; it also generates a leading singular term, |t|^{2\beta}, in the coexistence curve diameter, where t\equiv (T-T_{\scriptsize c}) /T_{\scriptsize c}. The behavior of various special loci, such as the critical isochore, the critical isotherm, the k-inflection loci, on which \chi^{(k)}\equiv \chi(\rho,T)/\rho^{k} (with \chi = \rho^{2} k_{\scriptsize B}TK_{T}) and C_{V}^{(k)}\equiv C_{V}(\rho,T)/\rho^{k} are maximal at fixed T, is carefully elucidated. These results are useful for analyzing simulations and experiments, since particular, nonuniversal values of k specify loci that approach the critical density most rapidly and reflect the pressure-mixing coefficient. Concrete illustrations are presented for the hard-core square-well fluid and for the restricted primitive model electrolyte. For comparison, a discussion of the classical (or Landau) theory is presented briefly and various interesting loci are determined explicitly and illustrated quantitatively for a van der Waals fluid.Comment: 21 pages in two-column format including 8 figure