GENEVA — Swine flu is now formally a pandemic, a declaration by United Nations health officials that will speed vaccine production and spur government spending to combat the first global flu epidemic in 41 years.
Thursday's announcement by the World Health Organization doesn't mean that the virus is any more lethal — only that its spread is considered unstoppable.
Since it was first detected in late April in Mexico and the United States, swine flu has reached 74 countries. Most people who catch the bug have only mild symptoms and don't need medical treatment.
WHO chief Margaret Chan made the declaration after the U.N. agency held an emergency meeting with flu experts. She said she was moving to Phase 6, the agency's highest alert level, which means a pandemic is under way.
But the pandemic is "moderate" in severity, she noted, with the overwhelming majority of patients experiencing only mild symptoms and a full recovery.
Unlike seasonal flus, which have taken their highest toll on the very young and the very old, Chan said, most severe cases of the H1N1 virus have involved people between ages 30 and 50; overall, the majority of all infections have occurred in people under 25.
The last pandemic, the Hong Kong flu of 1968, killed about 700,000 people worldwide. Ordinary flu kills 250,000 to 500,000 people each year, international health officials have said.
The pandemic decision might have been made much earlier if WHO had had more accurate data about swine flu's rising sweep through Europe. Chan said she called the emergency meeting with flu experts after concerns were raised that some countries, such as Britain, were not accurately reporting their cases.
Many health experts said that the world has been in a pandemic for weeks but that WHO became too bogged down by politics to declare one. In May, several countries urged WHO not to declare a pandemic, fearing it would cause social and economic turmoil.
WHO will now recommend that pharmaceutical companies make swine flu vaccine.
Information from the New York Times was used in this report.