Your immune system is designed to have a “memory” of previous infections. When your body encounters a microbe that has previously caused an infection, it enhances its production of white blood cells and antibodies to prevent infection a second time. When you get vaccinated, you “trick” your body into thinking that it has been infected by a particular microbe—thus boosting its own defenses against infection.

Why vaccination is important

The majority of Americans who die each year from vaccine-preventable diseases are adults. Get the shots you need to protect yourself. Vaccines are a very effective way to prevent the suffering (and costs) associated with vaccine-preventable infections, including the flu, pneumonia, human papillomavirus (HPV), and hepatitis B. Learn which vaccines you need to stay healthy.

Vaccines are among the safest medical products available. The potential risks associated with the diseases these vaccines prevent are much greater than the potential risks associated with the vaccines themselves. The most common side effects are sore arms and low-grade fevers.

Get your flu shot.

The best way to prevent influenza is by getting vaccinated each year. An annual flu vaccine is necessary because flu viruses are constantly changing. (It’s not unusual for new flu viruses to appear each year.) The flu vaccine is formulated to keep up with the flu viruses as they change from year to year.

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