Flu cases on the west coast are rising months earlier than normal, prompting US health experts to emphasize the importance of the annual vaccine. Typically, flu activity ramps up in December and peaks in February, but this season has kicked into action earlier, with higher positive cases than usual recorded.
Early Rise in Flu Cases
Several experts attribute the early seasonal start to a new mutation of the influenza A strain H1N1, which was responsible for the 2009 swine flu pandemic. This strain has accounted for 242 of 300 influenza viruses reported by public health laboratories to the Centers for Disease Control and Prevention (CDC) to date.
In California, the influenza test positivity rate has surged to 9.65% as of October 10, compared to just above 1% during the same period in the past two flu seasons. Additionally, Utah has recorded 242 influenza A cases as of October 11, a significant increase from 10 cases this time last year, according to Germ Watch, an Intermountain Health database. Parts of central Oregon have also experienced a surge in influenza A cases.
