Launching an effective bird flu vaccine quickly could be tough, scientists warn

The federal government says it has taken steps toward developing a vaccine to protect against bird flu should it become a threat to humans. (skodonnell/Getty Images)

The bird flu that's now spreading among cows doesn't yet appear to pose an imminent threat to most people. Scientists say the virus would need to mutate significantly to be able to transmit easily from human to human.

But federal health officials say they've started trying to develop a vaccine to protect people just in case a pandemic erupts.