WASHINGTON — The Senate confirmed the nomination of Kathleen Sebelius as secretary of health and human services on Tuesday, allowing President Obama to fill the last vacancy in his cabinet with a seasoned politician who will take charge of the fight against swine flu. The vote was 65 to 31. Among the nine Republicans who voted for Ms. Sebelius was Senator Arlen Specter of Pennsylvania, who announced on Tuesday that he was becoming a Democrat. Besides directing federal efforts against swine flu, Ms. Sebelius will lead the administration's campaign for universal health insurance.