Department of Animal Health officials in Vietnam have said no new outbreaks of bird flu have been detected among poultry for more than three weeks. However, the department warned that there was still a high risk of future flare-ups of the virus, in the country hardest hit by the disease.

A report by Dow Jones said the Vietnamese government deems the virus to be contained if no new outbreaks have been reported in 21 days. The last two areas to conform to those requirements were the northern provinces of Ha Giang and Cao Bang on the Chinese border. The virus had affected some 21 provinces in the country.

Hoang Van Nam, deputy director of the national Department of Animal Health, was quoted by Dow Jones saying: “We have not been able to eradicate the bird flu virus, which still exists in the environment, and the risk of bird flu recurrence remains very high, particularly over the next two months when outbreaks have peaked during January and February in previous years.”

Nam also warned that the increased movement of poultry and people and cooler weather around the Lunar New Year at the end of January could spark a further outbreak.