The pandemic H1N1 influenza strain, which first surfaced in 2009, appears to be the predominant circulating virus this flu season, the CDC has notified healthcare providers. In November and December, several cases of severe respiratory illness associated with the virus were reported, including ITU admissions and fatalities.
Young and middle-aged adults may be disproportionately affected by this strain. The CDC reminds clinicians that everyone aged 6 months and older should receive an influenza vaccine; all available formulations protect against H1N1.
The agency says that anyone who has not yet received a flu vaccine should get one now.