APPLYING TIME SERIES SIR MODEL TO INVESTIGATE EPIDEMIOLOGY AND CALCULATE MINIMUM VACCINATION COVERAGE AGAINST MEASLES IN IRAN

Measles is one of the most contagious viral diseases among infants. In recent years, studying the infectious diseases using dynamic computational models has gained special importance in epidemiologic studies. One of these models is known as sensitive-infectious-resistant or SIR, which has been designed based on mathematics for answering numerous questions on emersion and silence of a disease epidemics. The present study is aimed to apply this model on epidemiology of measles in Iran, determine occurrence or non-occurrence of epidemy, and calculate the minimum vaccination coverage in Iran during 1997-2011. The data used in this study was collected from among the information and statistics of the contagious diseases of the Disease Management Center of Iran. By applying the epidemiologic SIR model on measles in Iran, values of the parameters of basic reproduction ratio (Ro) and probability of vaccination coverage (P) for infection in various years were obtained. Based on the Ro results, it can be said that measles disease is still in the epidemic phase, and country's required vaccination coverage for haltering measles epidemy has got a decreasing trend. The predicted values of P for the years 2008 and 2011 are 9.6714543 and 10.08324, respectively. Regarding the obtained results, it is suggested to the Health Ministry to establish a taskforce in order to make decisions on revision and amendment of the measles vaccination program