A federal government Website managed by the National Vaccine Program Office,
U.S. Department of Health and Human Services (HHS)
Vaccines Protect You
Vaccines do an incredible job of protecting you from serious diseases like whooping cough and measles.
Have you ever wondered how vaccines actually work? Vaccines help your immune system do its job better and faster. And that protects you from serious diseases.
What is the immune system?
The immune system is a network of cells, tissues, and organs that work together to defend the body from harmful germs. When bacteria, viruses, and other germs invade your body, they multiply and attack. This invasion is called an infection. Infections cause the diseases that make you sick.
Your immune system protects you from the disease by fighting off the invading germs.
How does the immune system work?
Your immune system is always on patrol in your body. When it comes across an invading germ, it attacks that germ. This is called an immune response.
Here’s how an immune response works:
- Your immune system sounds the alarm so your body knows there’s an infection.
- It begins releasing antibodies to fight the germ — think of antibodies as soldiers designed to fight off the specific germ you have. This process can take a few days.
- The antibodies work to attack, weaken, and destroy the germ.
- Afterwards, your immune system remembers the germ. If the germ invades again, your body can recognize it and quickly send out the right antibodies so you don’t get sick!
- This protection against a certain disease is called immunity. In many cases, immunity lasts your whole life.
How do vaccines work?
Vaccines help your immune system fight infections faster and more effectively. When you get a vaccine, it sparks your immune response, helping your body fight off and remember the germ so it can attack it if the germ ever invades again. And since vaccines are made of very small amounts of weak or dead germs, they won’t make you sick.
Vaccines often provide long-lasting immunity to serious diseases without the risk of serious illness. Learn more about getting vaccinated.
Which is safer: Natural immunity or immunity after getting a vaccine?
Vaccines are much safer. Natural immunity happens after you get sick with a disease. But diseases can be serious — and even deadly. A vaccine protects you from a disease before it makes you sick.
Vaccines don’t just protect you — they also protect the people around you
Did you know that some people — like infants and people with weak or failing immune systems (like people with HIV/AIDS or cancer) — may not be able to get many of the vaccines that protect us from serious diseases?
The good news is that when you get vaccinated, you’re also protecting the unvaccinated people around you. This is called community immunity. Learn more about community immunity.
Last reviewed: December 2017