Changes in influenza vaccination rates among healthcare workers following a pandemic influenza year at a Japanese tertiary care centre

Background: Although influenza vaccination, which is a key part of a control plan to prevent nosocomial influenza transmission, is recommended for all healthcare workers (HCWs), the achievement of a high influenza vaccination rate among HCWs is a challenge. In Japan, there are limited data on influenza vaccination rates among HCWs. Moreover, the effect of pandemic influenza on influenza vaccination rates among HCWs following a pandemic year remains unclear. Aim: To determine influenza vaccination rates among HCWs at a tertiary medical centre in Japan, and to evaluate the need for further interventions to enhance the vaccination rate among HCWs. Methods: The 2005-2010 influenza vaccination rates among HCWs at a 550-bed, tertiary care centre in Sapporo, Japan were reviewed retrospectively using the hospital's occupational health service database. Findings: There was a gradual increase in the seasonal influenza vaccination rate in this population from 2005 to 2010, and a high vaccination rate among HCWs during the 2009-2010 pandemic H1N1 influenza season. However, the seasonal influenza vaccination rate in 2010-2011 was significantly lower than that for the pandemic vaccine in 2009-2010, with doctors having the lowest vaccination rate among all HCWs. Conclusion: Pandemic influenza may not have a sustained effect on the uptake of influenza vaccination in subsequent years. Thus, vaccination rates among HCWs after a pandemic year still need to be monitored, and the implementation of interventions such as a mandatory vaccination programme should be considered to maintain consistently adequate vaccination rates.