WASHINGTON - Pennsylvania and New Jersey are among only seven states that earned top scores in a report on how well states have prepared for public-health emergencies.

The report concluded states had made significant progress since the terrorist and anthrax attacks in 2001, but critical gaps remain.

Seven states have yet to participate in a federal program to buy antiviral drugs for a potential flu pandemic. Thirteen states do not have adequate plans to distribute medical supplies from the Strategic National Stockpile.

The Trust for America's Health, a research group, looked at states' performance in 10 categories. Besides Pennsylvania and New Jersey, top scores went to Illinois, Kentucky, Nebraska, Tennessee and Virginia.

The lowest scores went to Arkansas, Iowa, Mississippi, Nevada, Wisconsin and Wyoming.

The report was funded by Plainsboro, N.J.-based Robert Wood Johnson Foundation, the nation's largest health-care charity.

The federal government has had difficulty evaluating how well states have used billions of dollars over the last six years to improve preparedness. The money went to upgrade laboratories, buy medical supplies, and conduct training exercises.

The Bush administration has encouraged states to stock up on antivirals, which reduce the severity of influenza. Under one program, the government will pay for a quarter of the cost of buying Tamiflu or Relenza, and states pay the remainder for a combined investment of about $680 million.

A spokesman for the Department of Health and Human Services said that states had until June 2008 to get their orders in. All states have told the federal government they plan on participating, he said.

However, Colorado, Connecticut, Florida, Massachusetts, Mississippi, North Dakota and Rhode Island have not yet purchased any antivirals. Several more have bought only a fraction of what they are entitled to.

"If a significant number of states don't pick up their share of responsibility, then the country as a whole is less protected," said Jeffrey Levi, executive director of Trust for America's Health.

The report also highlighted the need for 21 states to update their "Good Samaritan" laws to create liability shields for those who help others at the scene of an emergency.

Among other findings:

Flu-shot rates for the elderly dropped in 11 states.

Six states cut public health department budgets last year.

All 50 states and the District of Columbia held emergency drills with their health department and state National Guard.