The United Nations health agency today declared an end to the H1N1 pandemic but urged continued vigilance, cautioning that pandemics, like the viruses that cause them, are unpredictable.
The announcement follows an assessment by its International Health Regulations Emergency Committee, which met earlier today, as well as reports from several countries that are now experiencing influenza.
It comes a little more than a year after the agency first declared the start of the H1N1 pandemic. The new influenza virus spread with unprecedented speed, reaching 120 countries and territories in around eight weeks, according to WHO, which noted that cases were eventually reported in almost every country.
Dr. Chan said that globally, the levels and patterns of H1N1 transmission now being seen differ significantly from what was observed during the pandemic. Out-of-season outbreaks are no longer being reported in either the northern or southern hemisphere.
“Influenza outbreaks, including those primarily caused by the H1N1 virus, show an intensity similar to that seen during seasonal epidemics,” she noted.
Also, during the pandemic, the H1N1 virus crowded out other influenza viruses to become the dominant virus. “This is no longer the case. Many countries are reporting a mix of influenza viruses, again as is typically seen during seasonal epidemics.”
She noted that the start of the post-pandemic period does not mean that the H1N1 virus has gone away.
“Based on experience with past pandemics, we expect the H1N1 virus to take on the behaviour of a seasonal influenza virus and continue to circulate for some years to come.
“Pandemics, like the viruses that cause them, are unpredictable. So is the immediate post-pandemic period,” she stated.
She stressed that continued vigilance is extremely important, and WHO has issued advice on recommended surveillance, vaccination, and clinical management during the post-pandemic period.