A mutated version of the seasonal strain of flu targeted by this season's vaccine has surfaced in a traveler entering Canada from Mexico, Reuters reports. The development complicates the tracking of the virus in Mexico, which has suffered the majority of infections and deaths. The variant was previously found in Canadian long-term care facilities, where it may have caused an unusually late flu outbreak in March.
"We wonder to what extent the profile of influenza-like illness initially reported from mid-March in Mexico may in part be attributed to this H3N2 variant, in addition to emergence of the novel A/H1N1 virus," Canadian researchers said in a report.
(More swine flu stories.)