BackgroundInfluenza vaccination is widely recommended for healthcare workers (HCWs) in European countries, but the coverage is not always satisfactory. In Finland, a new act was introduced in March 2017, according to which it is the employer's responsibility to appoint only vaccinated HCWs for servicing vulnerable patients.AimWe determined the influenza vaccination coverage among HCWs in Finnish acute care hospitals in three influenza seasons after introduction of the act.MethodsWe analysed data collected by an internet-based survey sent annually to all Finnish acute care hospitals and described the influenza vaccination coverage among HCWs during seasons 2017/18, 2018/19 and 2019/20. We calculated mean coverage per healthcare district and season.ResultsIn season 2017/18, 38 of 39 hospitals, in 2018/19, 35 of 36 hospitals and in 2018/19 31 of 33 hospitals provided data. The mean influenza vaccination coverage was 83.7% (SD: 12.3) in season 2017/18, 90.8% (SD: 8.7) in 2018/19 and 87.6% (SD: 10.9) in season 2019/20. There was no significant increase or decrease in the mean coverage across the three seasons. The differences between districts were only significant in 2018/19 (p < 0.005).ConclusionsThe coverage of influenza-vaccinated HCWs in Finnish hospitals was high in all three seasons and the current legal situation (semi-mandatory system) in Finland seems to provide a good background for this. Data collection should be maintained and improved for further monitoring.