Updated on Friday, July 03, 2009, 09:06 IST

Cancun, July 03: At least 337 people have died from swine flu, which has also sickened 80,000 others in 121 countries, the World Health Organisation (WHO) said on Thursday.

Keiji Fukuda, WHO Assistant Director-General, announced the agency's updated figures at a two-day summit on influenza being held in the Mexican resort city of Cancun.

Fukuda said most of the cases were of young people with prior health problems, but he warned that the future of the disease remained uncertain, including its severity, clinical patterns and the structure of the virus.

He said "flexibility" was vital as the international health community prepares for the evolution of the pandemic.

IANS