ASHINGTON, March 6 — The anthrax vaccine is safe and effective, and is likely to work even against strains of the bacteria that have been engineered as weapons, according to a new study that could clear the way for the Pentagon to resume its program of vaccinating all soldiers.

The study, financed by the Pentagon and made public today by the Institute of Medicine, an independent research institution that advises the federal government, is the most comprehensive study ever conducted of the vaccine's safety and effectiveness.

It found no evidence to support claims of soldiers who said they had been injured by their inoculations. But the study did say that the current vaccine, which is administered in six doses over 18 months, is "far from optimal," and urged the Defense Department to accelerate its research to find a new one.

Even so, Pentagon officials said they were delighted by the outcome.

"This is good news for service members," Lt. Col. John Grabenstein, who runs the military's immunization program, said after the study was released. "The bad guys have the anthrax weapon and the vaccine that we are using works."

The anthrax vaccine, which was most recently in the news when it was offered to postal workers and Congressional employees who were exposed to anthrax in the bioterrorist attacks, has been mired in controversy since the Pentagon's mass vaccination program began in 1998.

More than 400 soldiers have been disciplined for refusing to take the vaccine, and the program was all but suspended when the sole manufacturer, BioPort of Lansing, Mich., failed Food and Drug Administration inspections.

The manufacturing deficiencies have been corrected. A scientist close to BioPort said today that Pentagon officials had informed the company that "the Pentagon was waiting only for this report to sign off on a resumption of mass vaccination."

But Dr. William Winkenwerder, the assistant secretary for health affairs, said a decision on whether, or how, to resume the program would be announced within "a couple of weeks at the outside."

While the vaccine can cause malaise and muscle pain that may be temporarily disabling, the most common side effects are redness and swelling at the injection site, said the panel of experts who conducted the Institute of Medicine study. The panel said the reactions were no more serious than for other vaccines given to adults, such as tetanus shots.

"Our committee concluded that it is sufficiently safe to be useful," Dr. Brian L. Strom, a University of Pennsylvania epidemiologist who was the chairman of the panel, said at a news conference.

The BioPort vaccine, first approved by the F.D.A. in 1970, relies on technology that dates from the 1950's. The Defense Department is working on an alternative, and clinical trials may begin as early as this year, Colonel Grabenstein said. But it could be five years before a new vaccine is approved for use.

Meanwhile, BioPort, the government's only supplier, has produced about 500,000 doses of the vaccine under an unusual arrangement in which the Defense Department pays the salaries of the company's employees. Dr. Winkenwerder said today that the government needed to give the company financial help to keep it viable while its plant was essentially shut down by the F.D.A.

After the report was released, the company's president, Robert G. Kramer Sr., said, "This is a great day for BioPort."

The vaccine's critics said today that the study was flawed because soldiers were typically reluctant to complain about adverse reactions, and so the medical literature did not reflect the true extent of the vaccine's problems.