This year, there are 122 million doses of flu vaccine available - the most ever offered, Allen said.
But this season's batch of flu vaccines might not be as effective as usual.
Scientists determine which flu strains to make vaccines for nearly a year before flu season starts, Allen said. Small changes occur in the viruses over time, which leads to the emergence of new strains - the reason the CDC recommends people get the flu shot every year.
The problem is that one of the flu strains scientists thought would be prominent this season, A/Wisconsin, mutated to form a different strain, A/Brisbane, which is not in this year's round of vaccinations, Allen said.
People who get vaccinations this season will have a 50-50 chance of being protected against A/Brisbane, Allen said.
"Even if you do get A/Brisbane, if you get a vaccine, you won't get as sick," Allen said.
When the vaccine and flu strains aren't an exact match, antibodies are still made in response to the vaccine and can offer protection against other strains, Allen said.
In Maryland, health officials are not required to report cases of the flu, said Washington County Health Department spokesman Rod MacRae. The Health Department tracks flu cases but does not keep data on the occurrence of specific strains, MacRae said.
So far for 2008 there have been 152 cases of the flu reported to the Washington County Health Department. Complete figures for 2007 were unavailable, MacRae said.
The Health Department administers between 5,000 and 6,000 doses of flu vaccine each year, MacRae said.
MacRae said historically, children have accounted for few of the vaccinations offered locally. But given the CDC's new recommendation, the Health Department will do more this summer to encourage families to have children vaccinated.
Previously, seniors citizens were the main target of flu vaccination campaigns, because they are more prone to adverse responses caused by flu, MacRae said
Allen said studies have shown it could also be beneficial to vaccinate a larger group of younger people, because they are likely to catch and spread the disease and they have stronger immune systems.
MacRae said it was an idea that had been floating around health circles for some time. He said the reason for the expansion was simple.
"It's the children who are getting the old people sick," MacRae said.
MacRae said the health department has already ordered adult flu vaccines for the 2008-09 flu season but has not yet ordered its children's vaccines because of the new recommendations.
"We're not sure how many more to order," MacRae said.
Allen said the CDC is encouraging health officials to act on the recommendation by next flu season, if they have enough vaccines to do so. The CDC hopes the recommendations will take full effect by the 2009-2010 flu season, Allen said.