PREVENTING EPIDEMICS IN A COMMUNITY OF HOUSEHOLDS

The occurrence of epidemics of vaccine-preventable diseases, and the i mmunization coverage required to prevent them, is affected by the pres ence of households and heterogeneity in the community. We consider a c ommunity where individuals live in households and are of different typ es, according to infectivity and/or susceptibility to infection. We de scribe a method for computing the critical immunization coverage to pr event epidemics in such communities and discuss the effectiveness of i mmunization strategies. In a heterogeneous community where individuals live in households several immunization strategies are possible and w e examine strategies targeting households, randomly selected individua ls, or groups with highly intense transmission, such as school childre n. We compare estimates of the critical immunization coverage if we as sume that disease is spread solely by random mixing with estimates whi ch result if we assume the effects of the household structure. Estimat es made under these two sets of assumptions differ. The results provid e insights into the community effects of vaccination, and the househol d structure of the community should be taken into account when designi ng immunization policies.