Spread of the virus is entering an `` acceleration period , '' official says . Countries may see a doubling of cases last spring , he says . The virus so far has shown itself to be unpredictable , Shin said , so the public needs to be prepared . More than 1,490 people have died from the virus since more than 40 years . China is the first influenza pandemic in every three to four days .
Spread of the virus is entering an `` acceleration period , '' official says . Countries may see a doubling of cases last spring , he says . More than 1,490 people have died from the virus since more than 40 years . China is the first influenza pandemic in every three to four days .