Pandemic influenza A(H1N1)pdm09 improves vaccination routine in subsequent years: A cohort study from 2009 to 2011

► Being vaccinated in 2009 enhanced the vaccination probability in 2010 and 2011. ► This effect was seen for seasonal as well as pandemic A(H1N1)pdm09 vaccinations. ► The positive effects for the same cohort were still found after two years. ► The A(H1N1)pdm09 vaccinations did not disturb, but enhanced vaccination routine.