The hope is that the avian strain, known as A(H5N1), will peter out.

Health officials worry that the avian strain may combine with human influenza to create a new virus.

Pandemic influenza, whether it arises from current avian strains or less obvious sources, is one of the greatest threats facing the world.

Might the bird flu strain have a lower replication temperature than other avian strains?

The scientists discover that "the vaccine developed previously for the avian strain will only provide partial protection," the plan states.

The avian strain has affected what influenza experts say is "an unprecedented" number of bird species.

That gives today's avian strain two routes to wreak havoc among humans.

Nobody knows whether the avian strain now under the spotlight will become a big threat to humans.

Laboratory studies suggest that the vaccine developed previously for the avian strain will only provide partial protection against the new virus.

The most recent common ancestor of the avian strains was placed at 6000 years ago.