WHO spokesman Gregory Hartl said it was too soon to draw any conclusions from the death toll as experts needed to monitor a full year of the disease, which the WHO declared a pandemic in June after the strain was first detected in April. Health experts need to observe the behavior of the virus during the traditional January-February peak of the influenza season in the northern hemisphere.
Most people who catch the H1N1 virus suffer mild symptoms. "There is a small subset of cases that do and can progress quite rapidly to severe disease and this is sometimes in the space of less than 24 hours and it then becomes a big, big challenge to save the people," Hartl said.
"This disease continues to cause concern because it doesn't act exactly like seasonal influenza and because it doesn't affect the same groups who are affected by seasonal influenza."
In the USA, 86 children have died of H1N1 since April. The seasonal flu typically kills between 46 and 88 children in a full year, according to CDC data.
6 percent of all doctor visits are for flu-like illnesses, levels not normally seen until later in the fall. Half of the all the child deaths have been in teenagers.
Drug manufacturers have told health officials to expect at least 25 percent less vaccine by the end of the month than anticipated. Instead of the 40 million doses projected by the end of October, only 28 million to 30 million doses may be available, said Dr. Anne Schuchat, director of immunization and respiratory diseases.