The H1N1 virus responsible for the 2009 global pandemic is back. State health officials from across the nation say the resurgence is resulting in a dramatic rise in flu deaths in young and middle-aged adults and in children this season.
While the reported death tolls so far are only a fraction of what they were four years ago, they are significantly higher than last year. The federal Centers for Disease Control and Prevention said the flu has been killing at epidemic levels since mid-January.
With one month to six weeks to go in the flu season, which typically ends in March or April, the CDC said the number of people visiting doctors and hospitals for flu-like symptoms is declining overall, but some states are continuing to see high levels of flu activity, or even increases. Although the flu usually disproportionately affects the very old and very young, this season 60 percent of those hospitalized for influenza have been age 18 to 64.
H1N1, also known as "swine flu" because it was originally a respiratory illness in pigs, has been popping up in some patients seasonally for the past few years, but this is the first flu season since the 2009 pandemic in which it has been circulating so widely.
The outbreak has been especially severe in California. There have been 243 deaths of residents younger than 65 so far this year. An additional 41 cases were reported but have not been confirmed. In the 2012-13 season, there were 26 deaths by this time, and in the 2011-12 season there were nine deaths. In the 2009-10 season, there were 527 deaths.
In the San Francisco Bay Area, some hospitals have been so inundated with patients complaining of flu-like symptoms that triage tents have been set up on their lawns to prevent them from spreading the virus to others in the medical centers. In Sacramento, Calif., intensive care units are overflowing with those with breathing issues, water in their lungs, organ failure or other complications from the flu.
Scientists have been working on a universal flu vaccine to offer long-term protection and remove the need to get a shot annually, but even the most optimistic say such a product is years away.
HINI's re-emergence in the United States comes as even more virulent strains that are combinations of several genetic strains begin to appear around the world. In recent months, the World Health Organization has been tracking more than 300 cases, mostly in China, of people infected by a dangerous avian influenza strain, H7N9.
More alarming news came this month: Chinese officials, writing in the journal Lancet, said they identified yet another brand-new bird flu, H10N8, in a 73-year-old woman in Nanchang, a city in Chinia's southeast.