Weekly antibiotic prescribing and influenza activity in Sweden: a study throughout five influenza seasons.

Influenza often leads to bacterial complications that require treatment. It may also be confused with bacterial respiratory infections, leading to unnecessary prescription of antibiotics. In this first study on the relationship between influenza and antibiotic utilization for a whole country, weekly data on verified influenza cases in Sweden were compared to weekly sales of antibiotics for 5 influenza seasons 1997-2002. The peak of influenza activity occurred during the winter. In 4 out of the 5 monitored influenza seasons it occurred in February-March. The fluctuation of antibiotic utilization was relatively constant over the years with peaks before Christmas and in February-March. There were no obvious differences in the total amount of antibiotics dispensed over the years that could be related to influenza activity, but a coincidental relationship between the peaks of diagnosed influenza cases and the peaks of antibiotic utilization was indicated, especially for older age groups.