Romans 13:1-2:

Let every soul be subject unto the higher powers. For there is no power but of God: the powers that be are ordained of God.
Whosoever therefore resisteth the power, resisteth the ordinance of God: and they that resist shall receive to themselves damnation.

See also:

Should Christians Get Flu Shots?
Can I Get Healed of Alcoholism, Drug Abuse, Pornography and Homosexuality?
Objection: Teaching Grace Gives People a License to Sin