Effectiveness of an influenza vaccine used in Poland in the 1998-1999 influenza season

The aim of this study was to evaluate the effectiveness of the influenza vaccine used at the Proelmed Medical Center, Poland during the influenza season 1998-1999. The study randomised patients attending the Proelmed Medical Center, Poland to receive influenza vaccination or not. Volunteers were monitored for the following 6 months by interviews at which systemic and local symptoms were recorded. 193 volunteers were randomised to receive influenza vaccine and 206 to the control group. In the vaccinated group, 7 cases (3.7%) of influenza were recorded, compared to 59 cases (28.6%) in the unvaccinated group. Respiratory disease other than influenza occurred in 29.5% of the vaccinated group and 34.5% of the unvaccinated group. Vaccinated patients had a total of 62 days off sick due to influenza, compared to 467 days for the unvaccinated patients. No unexpected adverse events were reported. The influenza vaccine used is highly efficacious in protecting against influenza infection leading to absenteeism from work, and has a good safety profile.