Mysteriously, flu season seems to be hitting states along America’s Pacific coast over two months early this year—based on an unusually high spike in the percentage of positive tests for influenza collected by the U.S. Centers for Disease Control and Prevention (CDC). Both the timing and the location are unusual, according to medical researchers, although an explanation appears to be emerging.

The head of the University of Washington’s Division of Infectious Disease Diagnostics, Alex Greninger, told CNN that as much as 98% of the flu samples now arriving at this lab derive from the once infamous “swine flu” strain , H1N1, albeit with a tricky new mutation. Labelled G155E, the mutation spurring this emerging flu wave seems to prevent the virus from being recognized by some preexisting human antibodies, according to Greninger, including those built up by strains used to create this year’s round of flu shots.

Greninger, a virologist, advised the public to nevertheless get their flu shots early.…