Written by the Fiveable Content Team • Last updated September 2025
Written by the Fiveable Content Team • Last updated September 2025
Definition
An attenuated vaccine contains live pathogens that have been weakened so they cannot cause disease in healthy individuals. These vaccines stimulate a strong and lasting immune response.
5 Must Know Facts For Your Next Test
Attenuated vaccines are often used to protect against viral infections affecting the nervous system, such as polio and measles.
These vaccines can provide lifelong immunity with just one or two doses.
They work by mimicking natural infection, thus stimulating a comprehensive immune response including both humoral and cellular immunity.
Attenuated vaccines must be stored carefully as the live pathogens can revert to a virulent form if not handled properly.
Individuals with compromised immune systems generally should avoid live attenuated vaccines due to the risk of serious infection.