By Joseph W. Stubbs

Widespread immunization, also known as vaccination, is one of the most significant public-health achievements of the past 100 years. Vaccines have eradicated or significantly reduced the incidence of many life-threatening diseases, including polio, measles, and chicken pox.

Despite these achievements, though, hundreds of thousands of American adults get sick, miss work, or die every year because of vaccine-preventable diseases or their complications.

With all the talk about the H1N1 flu vaccine, now is a good time to remember that vaccinations are not just for children. Immunization recommendations begin soon after birth and continue throughout one's life.

In the United States, adults are 100 times more likely to die from vaccine-preventable diseases than children, who are vaccinated at a much higher rate. Adult immunization rates range from 26 percent to 69 percent, depending on the vaccine and the target group. By contrast, immunizations recommended for children between the ages of 19 months and 35 months reach rates of at least 90 percent in most cases.

Immunizations are a safe, effective, and simple way to prevent infectious diseases and maintain maximum protection against them. They spare people from serious illness and potentially save thousands of dollars in health-care costs. But many adults are unaware of the benefits of vaccines, the need for booster doses, and the availability of newer vaccines.

Seasonal flu is a prime example. Every year in the United States, about 36,000 people die from flu-related causes, and more than 200,000 are hospitalized for flu-related complications. And while an annual vaccination against seasonal flu is recommended for about 83 percent of the U.S. population, less than 40 percent of the population got the 2008-09 flu vaccine.

Seasonal flu activity can start as early as September, so the best time to get vaccinated is throughout the fall and winter. Flu viruses change often, so the seasonal flu vaccine is updated each year to make sure it's as effective as possible. (The H1N1 vaccine, when it becomes available, will protect only against H1N1 flu.)

And while it is important to get the seasonal flu vaccine now, flu viruses can circulate well into the spring and summer. People who are unable to get vaccinated now can do so as late as March.

In addition to seasonal and H1N1 flu, the list of vaccines that adults should discuss with their physicians includes those against pneumococcal pneumonia, diphtheria-tetanus-pertussis, hepatitis A and B, measles-mumps-rubella, chicken pox, meningococcal disease, human papillomavirus, and shingles.

By staying up to date on the recommended vaccines, adults can protect themselves, their families, their friends, and their communities from life-threatening diseases.

Dr. Joseph W. Stubbs is president of the Philadelphia-based American College of Physicians. For more information, see www.acponline.org.