“A new virus is responsible” for the cases reported in Mexico and the US, AFP Saturday quoted WHO Director General Margaret Chan as saying.

How the situation will evolve is “unpredictable,” she said, urging other countries to “increase vigilance.”

Vietnam’s Preventive Health and Environment Bureau under the Health Ministry Saturday asked all health facilities to keep a close watch on any case suspected of contracting the H1N1 swine influenza virus.

Bureau head Nguyen Huy Nga warned the pandemic could penetrate into Vietnam through the import of swine through border gates.

Human outbreaks of H1N1 swine influenza virus were recorded in the US in 1976 and 1988, when two deaths were recorded, and in 1986. In 1988 a pregnant woman died after contact with sick pigs, an AFP report quoted the WHO as saying.

The report said that in recent years, the global focus for a pandemic has shifted to the H5N1 bird flu virus, which spread from poultry to humans and has killed 257 of 421 people infected by the virus since 2003.

Reported by Nam Son