Get out your tissues and your hand sanitizer: Flu season is upon us, say experts from the Centers for Disease Control and Prevention.

The CDC is urging people at high risk from encounters with the influenza virus to ask for flu shots right away. High-risk people include those age 65 and older, people with chronic medical conditions such as diabetes, heart disease, and lung disease, pregnant women, people who have suppressed immune systems, and healthcare workers. People who are living in shelters in the aftermath of Hurricane Katrina should also get the shots, because of their crowded conditions.

The CDC is recommending that healthy people under 65 wait until October 24 to get the vaccine, to make sure that people at risk have first crack at the vaccines. There is no hint of the shortages that occurred last year, when the United Kingdom shut down a major vaccine manufacturer right at the beginning of flu season and elderly people waited for hours in pharmacy lines. Every year, some flu vaccine doses get thrown away, says CDC Director Julie Gerberding.

Both the flu shot and the FluMist inhaled vaccine are available again this year. While anyone 6 months and older can get the flu shot, FluMist is only approved for healthy people age 5 to 49.

Young children are particularly vulnerable to influenza; children ages 6 months to 23 months with influenza have the same high rate of hospitalization as older adults who get influenza, says pediatrician Henry Bernstein. Last year nearly half of children in that age group were vaccinated. To protect children who are too young to get the shot, everyone they come in contact with should be vaccinated, Bernstein says.

Influenza can be caused by many strains of the flu virus. Each year, officials make a prediction about which strains are likely to be active during the next flu season and should be included in that year's vaccines. Based on the few influenza cases that popped up over the summer, this year's vaccine appears to be mostly right, Gerberding says. Three strains are included in the vaccine. Only one of the two influenza B strains that were active this summer is covered in the vaccine; but influenza A is a bigger worry, and the two influenza A strains are matched by the vaccine, Gerberding says. Even imperfect matches may give some protection, she says.

Besides the vaccine, all children know—or should know, whether or not they do it—how to keep from passing viruses around: Cover your mouth when you sneeze or cough, throw used tissues away, and wash hands often with soap and warm water or alcohol-based hand sanitizer.

Despite the obvious risk to themselves and their patients, many doctors, nurses, and other healthcare workers do not get vaccinated.

"It's at best embarrassing and at worst tragic" that less than 50 percent of the healthcare workers in the United States get vaccinated annually, Gerberding says. During the last flu season, only 36 percent of healthcare workers were vaccinated. Healthcare workers who don't get vaccinated run the risk of bringing flu home from work and infecting their families, and of passing the virus between patients. Someone who has been infected with the virus may pass it on for 24 to 48 hours before symptoms appear, says William Schaffner, head of the preventive medicine department at Vanderbilt University School of Medicine.

Find out more: Check out www.cdc.gov for information about influenza.