Determinants of high residual post-PCV13 pneumococcal vaccine-type carriage in Blantyre Malawi: a modelling study

摘要

Survey data and model framework, priors and transmission matrix. Seven age groups were modelled: 0, 1, 2, 3–5, 6–7, 8–9, 10+ years of age (circles), each divided into unvaccinated (top) and vaccinated (bottom). Labels mark ageing rates per age class; mark age-specific death rates; b marks births, at which point a proportion ( ) are vaccinated (purple); marks vaccine-induced protection, expressed as reduction in susceptibility to infection of vaccinated individuals (magenta); mark age-specific forces of infection; mark age-specific rates of clearance from infection; k marks catch-up vaccination (green). The transmission matrix used, with coefficients and , where is the specific coefficient for transmission within and between particular age groups. and are estimated when fitting the survey data. The informative priors used in the fitting exercise for mean (standard deviation) infectious periods (days) of 47 (1.8) for 0–2 years old; 34 (1.3) for 3–5 years old; 26 (1.4) for 6–8 years old; 26 (2.0) for 8+ years old. The posterior values of these periods (1/ , 1/ , 1/ , 1/ ) are estimated when fitting the survey data. Mean and standard error for carriage as reported in the observational study data (surveys) per age group (Additional file  : Table S7). S1 to S7 highlight the surveys 1 to 7. The * mark data that was not collected