Washington ? To ensure that all Americans get needed vaccinations, the government should require medical insurance to cover the shots and should provide vouchers to people without insurance, a panel of medical experts recommended Monday.

“It was uppermost in our minds to close the gap, to assure there was no one in this country who lacked the means to pay for vaccinations,” said panel member Sara Rosenbaum of the George Washington University.

The recommendation from the Institute of Medicine urges that all private and government medical insurance cover needed vaccinations, that the government subsidize that coverage and provide vouchers so people without insurance can get their shots.

The Centers for Disease Control and Prevention reported last week that just 75 percent of the nation’s toddlers are vaccinated on schedule against nine diseases for which shots are required by federal law.

Coverage varies widely among states and major cities, CDC said, with pockets of the country where far too few youngsters are up-to-date on their shots. Federal health officials urged communities to eliminate the disparities.

Currently the federal government spends about $1 billion annually to buy about half of childhood vaccines, which are primarily distributed through the states in programs such as Medicaid and Vaccines for Children. Additional money is also spent for some adult vaccines.

A reduction in the number of companies producing vaccines, however, has helped lead to shortages in the last couple of years. CDC has said it plans to establish a vaccine stockpile by 2006 to curtail such problems.

Offering a subsidy for the purchase and distribution of the vaccines also would provide a stable market, which would encourage manufacturers, the report said.

It noted that there were more than 25 companies producing vaccines for the U.S. market 30 years ago, while only five do so today.

While most health plans already cover vaccines, the report recommended changes in federal regulations to make sure that all do, covering insured children, adults aged 65 and over and people who have health disorders that place them at higher risk for vaccine-preventable disease.

How the changes would affect the amount of federal spending on vaccines was not immediately clear, although the report said it probably would increase because more people would be eligible for subsidized shots. It noted, however, that society would benefit from getting more people protected from disease, both in protecting them from sickness and guarding others from infection.