Since then, at least 17 states have lifted all previous restrictions, according to the Association of State and Territorial Health Officials. The states had reserved the vaccine for older adults, infants and people with chronic medical conditions.
Earlier this month, Maryland and West Virginia loosened restrictions on who can get flu shots, health officials said.
The age limit was lowered from 65 to 50, according to a Maryland health department news release. Also, people who provide home care to high-risk groups or to children, newborn to age 23 months, or household members of high-risk groups and children may get flu shots.
Pennsylvania has not loosened restrictions because the state needs at least 18,000 doses of the vaccine according to a survey, Pennsylvania Department of Health spokeswoman Jessica Seiders said.
Seiders said department officials hope to get more vaccine within two weeks. Some states did not need remaining doses from the Centers for Disease Control and Prevention and so Pennsylvania officials hope to get some of those declined doses, she said.
While states like Maryland and West Virginia lowered the age limit to 50, Pennsylvania hasn't been able to meet the needs of the initial high-risk population, Seiders said.
Once the needs of the high-risk population are met, state officials will consider whether to loosen restrictions on who can receive the vaccine, Seiders said.
Washington County Health Officer William Christoffel said the Washington County Health Department has 90 flu vaccine doses left after distributing 7,630 doses this flu season.
Last Friday, more than 300 people attended a flu clinic with the lowered age limit, Christoffel said.
"We have given out more vaccine this year than we've ever given out and we've given it out to the high-risk population," Christoffel said.
"We reached more people that are high risk than we've ever reached before" because of the restrictions, Christoffel said.
Christoffel said he thinks the state will lift flu shot restrictions and might do so before the CDC decides whether to lift all restrictions.
"Demand has dwindled here in Washington County," Christoffel said.
The number of reported influenza cases in Maryland has been increasing, with 389 lab-confirmed cases as of Jan. 22, said Greg Reed, Maryland Center for Immunization program manager.
Western Maryland is among four of five areas in Maryland that has had an increase in influenza-like illness, Reed said.
That is typical this time of year, Reed said.
It is not too late to get a flu shot, and Reed encourages people who are eligible to do so.
If demand increases, the county and state can get more vaccine, officials said.
To make an appointment for a flu shot, call the Washington County Health Department at 240-313-3296 or call your doctor.
Some health officials say the CDC should recommend that restrictions be lifted nationally.
"I'd like to see the door open as widely as possible at this point," said Dr. William Schaffner, chairman of preventive medicine at Vanderbilt University Medical Center.
CDC officials said there are no plans to do that just yet.
"Our major goal is definitely to protect as many folks as we can," said CDC spokesman Von Roebuck.
After the restrictions were initiated in October, many of the 98 million people in America's high-risk groups did not get vaccinated, and some states found additional supplies of the vaccine.
That led to surpluses, but the vaccine is only good for one flu season.
"Timing is critical," Schaffner said. "If we don't use it now and don't use it really quickly in the next couple of weeks, basically the influenza vaccination season is over."
The flu season has been extremely mild so far. As of mid-January, only 10 states reported widespread activity.
States that have lifted all restrictions include Alaska, California, Colorado, Kansas, Massachusetts, Michigan, Minnesota, Nebraska, New Mexico, New York, North Carolina, Oklahoma, Oregon, South Dakota, Utah, Wisconsin and Wyoming, according to the Association of State and Territorial Health Officials.
The Associated Press contributed to this story.