Authors:   J. Lara de Paz, I. Flores

Abstract

Through a small world complex network simulation epidemic lifespan of the influenza virus outbreak is analyzed considering an age-based vaccines distribution preference. Mexico´s City population was divided in three different groups ? all children aged 4-12 years; ? persons aged 2-64 with underlying chronic medical conditions; ? adults aged 65 years and older; The simulation model is based in the vaccines distribution to this three groups in a differential way, exploring which proportion would show the shortest epidemic duration, therefore being that one the more efficient distribution strategy. The results obtained through the simulation, would help to minimize epidemic damage as in 2009 with the A(H1N1) strain. Also any other influenza strain should be considered in order to develop a containment strategy. To set up the simulation model a homogeneous social contact network was considered, where every population group presents its own social behavior forming small clusters and also presenting a probability of being in contact with an agent of a different cluster, as happens in social groups. Based on Mexico?s city population, estimations show that the 28% presents underlying chronic medical conditions, health care institutions consider only the most acute disease such as diabetes mellitus, heart problems and some kinds of cancer. The population group aged between 4-12 years represents approximately also the 28% of the entire population, while adults aged 65 years and older represents hardly a 6.6%. These three considered groups represents the more vulnerable population to be infected by a respiratory transmission disease during an epidemic threshold situation. The agent based simulation was set up in the NetLogo software and was run under a full randomized factorial experiments design, results were analyzed by an analysis of variance. Final results show that epidemic duration lasts less when the schoolchildren population received the biggest proportion of vaccination rather than giving priority to persons with underlying chronic medical conditions as done now by the actual containment strategies. These results are consistent with the knowledge that an epidemic outbreak starts between the household population, and due to the higher social interactions that occur at schools, it is more probable that this population affects more in the epidemic propagation. The 2009 new AH1N1 influenza virus strain showed the weakness of the public health authorities in for planning a pandemic containment strategy. The outbreak of the new strain had expanded rapidly around the world by the current connectivity conditions. An optimal strategy was needed to design an adequate containment policy at the proper outbreaks moment. The most common ways to control an outbreak are vaccination and isolation, the first one represents public investments in acquiring enough amounts of doses, the decision of social isolation involves less expenses as much as promoting, but imply stopping many productive activities. One of the more affected sectors, as an example, would the touristic sector, which in Mexico has represented the third economical income in the past years (Mexico´s National Institute for Statistics Geography and Information, INEGI 2014 report). This means that before such a critical arrangement could be implemented, other containment strategies should be carry out. While influenza vaccine is the most effective tool for preventing