A vaccine is a biological preparation that provides active acquired immunity to a specific infectious disease. A vaccine usually contains a weakened or killed microorganism, its surface proteins, or one of its toxins. The vaccine stimulates the immune system so that it recognizes and destroys the microorganism. This response also helps your body remember how to fight the same pathogen in the future so that it doesn’t get sick again.
Most vaccines contain weakened bacteria, viruses, or toxin that has been grown in the laboratory until it no longer causes disease. Others contain nucleic acid, such as DNA or messenger RNA (mRNA), that has been extracted from the cells of living organisms. The mRNA in these vaccines provides the instructions that your immune system needs to create antibodies against them.
Vaccines reduce the number of people who become sick and need treatment in hospitals. They can also prevent outbreaks of diseases that put infants, young children, older adults and people with weak immune systems at risk for serious complications and even death.
There is a small percentage of people whose immune systems don’t respond to vaccination. However, most people can make antibodies to a germ and get immune to it. Getting vaccinated is important for you and your family, as well as other members of your community. When enough people are immune to a disease, it can’t spread and is considered eradicated. For example, polio and measles have been eradicated in the United States thanks to vaccination.
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