Suspension of organisms or fractions of organisms used to induce immunity against a disease.

VACCINE

Etymology (origin) of = vaccine

vacca -- latin for cow

How does a vaccination work?

1. primary immune response (formation of antibodies & memory cells)

2. pathogen is encountered again = rapid/intense secondary response

Why is vaccination often the only feasible way to control most viral diseases?

Viruses can't be treated with antibiotics

Antiviral drugs are limited

Primes the immune system before exposure.

Attenuated vaccine

• Live, weakened pathogens
• closely mimics infection
• long-lasting immunity
  • MMR vaccine

Inactivated (killed) vaccine

• Killed pathogen
• safer and requires boosters
• mostly humoral vaccine
  • Salk (injected) polio vaccine