LOS ANGELES - The 2009-10 H1N1 influenza pandemic is officially over, the World Health Organization said Tuesday.
"The new H1N1 influenza has largely run its course," Dr. Margaret Chan, the organization's director-general, said from Hong Kong. "We are now moving into the post-pandemic period."
Some localities may experience outbreaks of the pandemic H1N1 virus, commonly called swine flu, she said, but overall activity is expected to be about normal for the season. In particular, she noted, out-of-season outbreaks are no longer being observed in either the northern or southern hemispheres.
One notable characteristic of the swine flu was that it struck during periods when seasonal influenza is normally relatively dormant. It also proved more deadly to young people and children, unlike seasonal flu, which takes a higher toll among the elderly.
During its reign, the pandemic H1N1 virus displaced most seasonal flu viruses and became the predominant strain of virus - and often the only one - in circulation. Now, however, most localities are experiencing a normal mix of flu viruses, she said.
Worldwide, 18,449 people died of laboratory-confirmed pandemic H1N1 infections, according to the WHO, but the toll is thought to be much higher because most victims aren't tested.
The organization has been heavily criticized recently by some groups who charged that it overinflated the dangers of the outbreak.
Countries around the world have large supplies of unused vaccine against swine flu because the initial fears were not borne out.
But Dr. Chan said her agency followed its rules.