Herd immunity and pneumococcal conjugate vaccine: A quantitative model
ABSTRACT Invasive pneumococcal disease in older children and adults declined markedly after introduction in 2000 of the pneumococcal conjugate vaccine for young children. An empirical quantitative model was developed to estimate the herd (indirect) effects on the incidence of invasive disease among persons ≥5 years of age induced by vaccination of young children with 1, 2, or ≥3 doses of the pneumococcal conjugate vaccine, Prevnar® (PCV7), containing serotypes 4, 6B, 9V, 14, 18C, 19F and 23F. From 1994 to 2003, cases of invasive pneumococcal disease were prospectively identified in Georgia Health District-3 (eight metropolitan Atlanta counties) by Active Bacterial Core surveillance (ABCs). From 2000 to 2003, vaccine coverage levels of PCV7 for children aged 19-35 months in Fulton and DeKalb counties (of Atlanta) were estimated from the National Immunization Survey (NIS). Based on incidence data and the estimated average number of doses received by 15 months of age, a Poisson regression model was fit, describing the trend in invasive pneumococcal disease in groups not targeted for vaccination (i.e., adults and older children) before and after the introduction of PCV7.
Full-textDOI: · Available from: Walter A Orenstein, Sep 27, 2015
- SourceAvailable from: Elissa Schwartz
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- "However, to the best of the authors' knowledge, no mathematical epidemiologic model to characterize the indirect effect of infant PCV7 vaccination has yet been developed. The only study to estimate a measure of herd effect as a focal point of a quantitative model is that conducted by Haber and colleagues . This group developed a Poisson regression model designed to predict the expected yearly incidence of IPD for several age groups using the mean number of doses per 15-month-old child as an explanative variable. "
ABSTRACT: We developed an age-structured, transmission-dynamic, mathematical model to quantify the direct and indirect benefits of infant PCV7 vaccination. The model simulates the acquisition of asymptomatic carriage of Streptococcus pneumoniae and the development of fatal and non-fatal invasive pneumococcal disease (IPD) among vaccinated and unvaccinated individuals aged <2, 2-4, 5-17, 18-49, 50-64, and >or=65 years old. The model was parameterized using published US surveillance data, supplemented with data from published literature. The model predicts the observed incidence of IPD with good agreement and may be used to predict the impact of various vaccination strategies in the US or other populations yet to introduce PCV7.Vaccine 06/2009; 27(34):4694-703. DOI:10.1016/j.vaccine.2009.05.062 · 3.62 Impact Factor