Federal health officials say the U.S. expects to have 160 million doses of swine flu vaccine available sometime in October -- if all goes well.
That's despite continued bad production from manufacturers around the world. The chief ingredient for vaccine is grown in chicken eggs, and companies are getting far fewer doses per egg than is usual with regular winter flu.
Another complication: That 160 million estimate assumes a low dose will work. Studies will begin in a few weeks to see if this new vaccine will protect with a low dose or if people will need a higher one. Scientists also expect people will need two separate inoculations, about a month apart, for protection..