A stochastic simulation epidemic model based on discrete time intervals and appropriate for any infectious agent spread by person-to-person contacts is presented. The population is highly structured, allowing for five age groups and for subgroup mixing in families, neighborhoods. schools, and preschool playgroups as well as total community mixing. With proper choice of relative susceptibility by age, length of latency and infectivity periods, pathogenicity and withdrawal patterns, and the relative infectiousness of silent infections, the model becomes highly agent-specific. The model includes flexible immunization routines and variable vaccine response patterns. The model is applied to the 1957 Asian and 1968 Hong Kong pandemic strains of influenza A. The results of several schedules of immunization of school children are presented and compared for the two strains.
|Original language||English (US)|
|Number of pages||14|
|Journal||American journal of epidemiology|
|State||Published - Feb 1976|
Bibliographical noteFunding Information:
Type A influenzavirus is of highly justi-demic periods. The pandemics reflect the fied public health concern as a major cause emergence of major antigenic variants of of significant morbidity in the population type A virus, against which immunity at large and of mortality in the elderly and induced by previously prevalent strains is in persons with chronic illnesses. Current of small or no effect. The most recent knowledge concerning influenza epidemiol-examples of major antigenic shift were the ogy has been summarized recently (1). The H,N2 (Asian) and H3N, (Hong Kong) vari-occurrence of influenza A is characterized ants, which emerged in 1957 and 1968, by major, worldwide pandemics at inter-respectively. Once established, each new vals of 10 to 12 years and frequent lesser variant undergoes progressive but lesser wintertime epidemics during interpan-change (antigenic drift) during its period of dominance. Although effective vaccines final can be (and are) produced, they are useful o,njy .[fmade.with virus.of the,currently dominant subtype or variant and are most useful if they contain a currently prevalent strain of that variant _ , ij.ii. • ,L For the present, at least, vaccines are the only available specific measure for preven-orcontrol of influenza. In addition to c ., ,, ,. . ,, , formidable practical problems Such as COSt, acceptance, and supply, maximal benefit 152 Received for publication May 12,1975, and in form July 18, 1975 Abbreviations AR, attack rates, SAR, secondary attack rates This investigation was supported in part by Research Grant GM-16164 from the National Institutes of Health •Section of Medical Research Statistics, Mayo Clinic and Mayo Foundation, Rochester, MN 5-5901 'Department of Epidemiology, University of Washington, Seattle, WA 98195. • Division of Health Computer Sciences, University of Minnesota, Minneapolis, MN 55455.