Selection and quantification of infection endpoints for trials of vaccines against intestinal helminths.

Alexander, N; Cundill, B; Sabatelli, L; Bethony, JM; Diemert, D; Hotez, P; Smith, PG; Rodrigues, LC; Brooker, S; (2011) Selection and quantification of infection endpoints for trials of vaccines against intestinal helminths. Vaccine, 29 (20). pp. 3686-94. ISSN 0264-410X DOI: 10.1016/j.vaccine.2011.03.026

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: Vaccines against human helminths are being developed but the choice of optimal parasitological endpoints and effect measures to assess their efficacy has received little attention. Assuming negative binomial distributions for the parasite counts, we rank the statistical power of three measures of efficacy: ratio of mean parasite intensity at the end of the trial, the odds ratio of infection at the end of the trial, and the rate ratio of incidence of infection during the trial. We also use a modelling approach to estimate the likely impact of trial interventions on the force of infection, and hence statistical power. We conclude that (1) final mean parasite intensity is a suitable endpoint for later phase vaccine trials, and (2) mass effects of trial interventions are unlikely to appreciably reduce the force of infection in the community - and hence statistical power - unless there is a combination of high vaccine efficacy and a large proportion of the population enrolled.<br/>

Item Type: Article
Faculty and Department: Faculty of Epidemiology and Population Health > Dept of Infectious Disease Epidemiology
Faculty of Infectious and Tropical Diseases > Dept of Disease Control
Research Centre: Centre for Global Non-Communicable Diseases (NCDs)
Neglected Tropical Diseases Network
Tropical Epidemiology Group
Vaccine Centre
Centre for Statistical Methodology
PubMed ID: 21435404
Web of Science ID: 290977700010


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