As flu season is fast approaching, local health services are encouraging people to get vaccinated.

While health officials say it's impossible to predict how each flu season will play out, they do know which strains to expect.

"The one thing we do know about flu is it's totally unpredictable," said Jeff Diamond, spokesman for the Centers for Disease Control and Prevention in Atlanta.

Diamond said remnants of H1N1 strains from 2009 that led to one of the worst flu seasons in decades will still be circulating, as well as a subtype of influenza A known as the H3N2 strain and a B strain.

The Longstreet Clinic in Gainesville has already begun its annual walk-in flu shot clinic. It takes up to two weeks for the vaccine to provide immunity, so people are encouraged to get vaccinated early since flu season can begin as early as October.

Lorrie Caruana from Longstreet said everybody is encouraged to get vaccinated, especially children younger than 5, pregnant women, people older than 50, people with chronic illnesses and health care workers.

Sandy Bozarth, infection control coordinator at Northeast Georgia Medical Center, said people need to be vaccinated every year because the strains are constantly evolving.

"Since the flu virus strain continually changes, the severity and length of the season will depend on the match of the virus to the current year's vaccine, and that's why it's so very important that you get your flu vaccine every year," Bozarth said.

Vaccines are developed based on the strains from the previous year and are expected to be effective against those strains.

Health officials anticipate an abundant supply of vaccines to cover everyone wishing to get vaccinated.

"The vaccine that is out now, there's plenty of it," Diamond said.

"There's 166 million doses that are out and it is plentiful and safe and ready to go."

Caruana said the walk-in clinic has prepared for 600 vaccines.