BackgroundVaccination coverage rates against pandemic flu were far below those required by Italian Public Health Authorities.The aim of this retrospective study was to assess how the management of vaccination against pandemic flu in the Health District of Piacenza (Northern Italy) had conditioned the adherence of patients at risk to the H1N1flu immunization program.MethodsFrom a population of 27.018 children aged between 6 months and 16 years, 2361 pediatric patients considered at risk according to the guidelines of the Ministry of Health were enrolled to receive pandemic flu vaccination.Children enrolled in the immunization program were vaccinated with one of the following three options:A) by their pediatrician in his office after contacting him directly or by phoneB) by their pediatrician in his office or in a public Health District office with the assistance of a nurse after an appointment had been booked by patient’s parents using a dedicated free of charge phone numberC) by a doctor of the public Health District after an appointment had been booked as for option BResultsThe best outcomes of population vaccination coverage for pandemic flu were achieved when patients were vaccinated with option B (44.2%). For options A and C rates coverage results were 22.8% (OR 2,69) and 24.9% (OR 2, 39) respectively.ConclusionThe results of this study may be taken into account by the public health Authorities when planning the management of future immunization campaigns out of the usual vaccination schedule or in an emergency event.