Vaccines, Immunology and Clinical Trials

Live Attenuated and Inactivated Vaccines

Live vaccines use a weakened (or attenuated) form of the germ that causes a disease. Because these vaccines are so similar to natural infection that they help prevent, they create a strong and long-lasting immune response. Just 1 or 2 doses of most live vaccines can give you a lifetime of protection against a germ and the disease it causes.

• Live vaccines are used to protect against:
• Measles, mumps, rubella
• Rotavirus
• Smallpox
• Chickenpox
• Yellow fever

Inactivated vaccines use the killed version of the germ that causes a disease. Inactivated vaccines usually don’t provide immunity (protection) that’s as strong as live vaccines. So you may need several doses over time (booster shots) to get ongoing immunity against diseases.

Inactivated vaccines are used to protect against:

• Hepatitis A
• Flu (shot only)
• Polio (shot only)
• Rabies