A flu epidemic is gaining speed in Switzerland, the Federal Health Office announced on Friday.
The Sentinella system, an index that tracks infection rates on the basis of information submitted by doctors and health professionals across the country, showed a two-fold increase from the last week of 2008 to the first week of 2009.
Health officials say there are now 63 suspected cases of influenza per 100,000 residents. They consider it a national epidemic once there are 48 cases per 100,000 residents.
The respiratory virus has attacked somewhat later this season compared with last year but now seems to be spreading through most areas of the country. Only central Switzerland has so far reported few cases.
Federal health officials caution that the data could be skewed since many doctors closed their offices during the holidays.