More than a year after the alert was raised, the organisation’s director general Margaret Chan this morning announced that the world is no longer in phase six of pandemic epidemic alert.
She said the new H1N1 virus "has largely run its course."
The decision was based on reports of how much disease the virus was causing around the world.
Even though the virus is still in circulation and there are localized outbreaks in some places, such as India and New Zealand, it is not nearly as common as it was last year, she said.
But Ms Chan warned that flu is still very unpredictable and that children and pregnant women are particularly vulnerable.
“Based on available evidence, the H1N1 virus currently continues to pose a higher risk for severe illness in some groups, including young children, pregnant women and those with respiratory or chronic health conditions,” says guidance on the World Health Organisation website.
"As we enter the post-pandemic period, this does not mean H1N1 has gone away," Ms Chan said after a meeting of the International Health Regulations Emergency Committee in Hong Kong. She urged health authorities around the world to stay on the look out for a comeback and advised countries to make sure this year's usual flu vaccine also protects people against H1N1.
The WHO declared the pandemic in June 2009, making it the first official flu pandemic since 1968. The virus has killed more than 18,449 people and affected 214 countries.
Ms Chan admitted that the pandemic turned out to be far less serious than officials had originally feared over a year ago.
"This time around we have been aided by pure good luck," she said. "The virus did not mutate during the pandemic to a more lethal form. Widespread resistance to Tamiflu did not develop and the vaccine proved to be a good match with circulating viruses and showed an excellent safety profile."
The WHO is now running a string of investigations after being accused of exaggerating the risk the outbreak posed. Countries around the world spent billions on vaccine and other precautions.
An investigation by The British Medical Journal claimed that key scientists behind the organisation’s advice on stockpiling pandemic flu drugs had financial ties with companies which stood to profit. A spokesman for WHO said the drug industry did not influence its decisions on swine flu.