Health officials urge Americans to get vaccinated even though the illness was not severe last season. (Jacquelyn Martin/AP)

U.S. health officials are urging more Americans to get vaccinated against influenza for the upcoming flu season, adding that there is plenty of vaccine on hand.

More than 85 million doses of the vaccine had been distributed as of Sept. 14, and a total of about 135 million doses will be available, the nonprofit National Foundation for Infectious Diseases said.

The flu season can begin as early as October and last as late as May, according to the Centers for Disease Control and Prevention. Howard Koh, assistant health secretary at the Department of Health and Human Services, said there was no guarantee that the 2012-13 flu season would be mild, as the last one was.

“When it comes to flu, we can’t look to the past to predict the future,” Koh said at a news conference.

The 2012-13 vaccine has one strain in common with last year’s and two new ones.

Koh and officials from other health organizations, including the American Medical Association and the American Academy of Pediatrics, urged vaccination as a first-line defense against the flu. They also said hand washing and coughing into an elbow rather than a hand were important flu-fighting tools.

The overall U.S. vaccination rate for the last flu season was about 42 percent, according to CDC numbers released at the news conference. The figure is well below target rates of 80 percent for people ages 6 months to 65 years and 90 percent for those older than 65. Vaccine recommendations were expanded to all healthy adults two years ago.

Vaccination rates varied widely. For children between 6 months and 23 months, it was 75 percent, while just over a third of adolescents were inoculated, the CDC said. About 39 percent of adults were vaccinated.

Factors keeping people from getting vaccinated include fear that they will get sick from the vaccine, cost and lack of awareness, Koh said.