"It is a cohesive and comprehensive framework to improve our public health system and thereby reduce our vulnerability," said Tennessee Republican Sen. Bill Frist, who initiated the legislation along with Massachusetts Democrat Sen. Edward Kennedy.
Frist noted that the bill would help Americans feel safer and calmer at a time when nerves have been frayed by vague warnings of new terror attacks.
The Senate vote was 98-0, one day after the House voted 425-1. The White House supports the legislation and Bush is expected to sign it soon.
"Congress today sends the message in one unified and clear voice that this nation will not remain unprepared for the threat of bioterrorism," Kennedy said. "The front lines in the new war against bioterrorism will be our health care system."
The bill would spend $640 million to produce and stockpile smallpox vaccines for vast numbers of Americans in the event the eradicated disease is reintroduced by terrorists. The measure also expands the availability of potassium iodide for communities near nuclear plants to treat radiation poisoning in case of terrorist attack.
Meanwhile, a separate House bill aiming $29 billion at the fight against terrorism bogged down Thursday in an election-year dispute over the rising national debt.
Ultimate passage of that bill was still a virtual certainty. Both parties strongly support its spending for the Pentagon, intelligence, airport security, aid to U.S. allies and New York's recovery from the Sept. 11 attacks.
Mail service to Capitol Hill was stopped for six weeks after an anthrax-contaminated letter was discovered last October in an office of Senate Majority Leader Tom Daschle, D-SD. A second anthrax letter was discovered later addressed to Sen. Patrick Leahy, D-VT.
Anthrax-contaminated mail at post offices and elsewhere killed five people and sickened an additional 13 last year. And recent scares have occurred at the Federal Reserve and World Bank. The FBI is investigating but has not yet determined the source of the tainted letters.
"We saw, of course, the devastating impact of a biological incident with the anthrax incident," said Sen. Judd Gregg, R-NH.
The bill will pump more money into the National Pharmaceutical Stockpile - secret stashes of medicine at locations throughout the United States. It also will provide a total of $1.6 billion in grants to states for hospital preparedness and assessments of the vulnerability of local water systems.
"Because of the initiatives we approve today, American families can go to sleep tonight knowing that their security will be enhanced," said Kennedy.
Water utilities under the legislation will be required to develop emergency plans and submit them to the Environmental Protection Agency.
The Centers for Disease Control and Prevention will get $300 million under the legislation to upgrade its facilities.