A killed vaccine, also known as an inactivated vaccine, is a type of vaccine that uses a pathogen (virus or bacteria) that has been killed or inactivated. This means the germ is dead and cannot cause disease. The body still recognizes the dead pathogen and builds immunity against it.
Examples of Killed Vaccines
- Whooping cough (pertussis) vaccine: This is a classic example of a killed vaccine, using inactivated Bordetella pertussis bacteria.
- Polio vaccine (Salk vaccine): The original polio vaccine developed by Jonas Salk was a killed-virus vaccine. This differs from the Sabin vaccine which utilizes a live attenuated virus.
- Some influenza vaccines: Many influenza vaccines utilize killed viruses. The specific composition varies yearly to match circulating strains.
- Rabies vaccine: The rabies vaccine, used to prevent rabies after exposure to the virus, is another example of a killed vaccine.
How Killed Vaccines Work
Killed vaccines work by introducing the dead or inactivated pathogens to the immune system. This triggers an immune response, creating antibodies that will protect against the actual live pathogen if encountered later. While effective, they often require multiple doses for full immunity and might not provide the same level of long-lasting immunity as live-attenuated vaccines.
Several methods exist for inactivating pathogens, including heat, chemicals, and radiation. The choice of method influences the vaccine's effectiveness and safety.
Key Differences from Live-Attenuated Vaccines
Unlike live-attenuated vaccines, which use a weakened but live form of the pathogen, killed vaccines pose significantly less risk to immunocompromised individuals. This is because they cannot replicate or cause disease. However, they may require booster shots to maintain long-term immunity.
The reference material mentions the use of proteins or other small pieces of viruses or bacteria in the creation of killed vaccines. This highlights that not the entire microbe is necessary to generate an immune response.
