WASHINGTON (Reuters) - The first roll-out of vaccines against the new swine flu virus will be 3.4 million doses of MedImmune's needle-free nose spray, the U.S. Centers for Disease Control and Prevention said on Friday. The CDC's Dr Jay Butler said the vaccines would be distributed the first week of October. "Initially we anticipate that 3.4 million doses of vaccine will be available," Butler told a telephone briefing. "We estimate that the amount of vaccine that will be available will increase through October." He said eventually delivery would rise to about 20 million doses a week. The United States has...