What are living vaccines and killed vaccines?

What are living vaccines and killed vaccines?

• A. Living vaccines contain attenuated bacteria or viruses; killed vaccines contain inactivated pathogens.
• B. Living vaccines contain inactivated pathogens; killed vaccines contain attenuated organisms.
• C. Both are the same; there is no difference.
• D. Living vaccines do not provoke immune response.

Answer: (A)

The essential idea is the form of the agent used in the vaccine. Living vaccines use attenuated (weakened) bacteria or viruses that can still replicate in the vaccinated person, though they are not capable of causing disease. Because they can replicate, they present the immune system with a broad set of antigens in a way that closely resembles natural infection, which often leads to a strong and long-lasting immune response with memory. They can even induce mucosal immunity when given through certain routes, but they carry a small risk to people with weakened immune systems and, rarely, can revert to a harmful form; they also tend to require careful storage. Killed vaccines use pathogens that have been inactivated and cannot replicate. They still provoke an immune response, but typically not as robust or durable as live vaccines, so they usually require additional doses and sometimes adjuvants to boost protection. They are generally safer for immunocompromised individuals and do not carry a risk of reversion to virulence, though they don’t stimulate as strong a cellular response as living vaccines.

The essential idea is the form of the agent used in the vaccine. Living vaccines use attenuated (weakened) bacteria or viruses that can still replicate in the vaccinated person, though they are not capable of causing disease. Because they can replicate, they present the immune system with a broad set of antigens in a way that closely resembles natural infection, which often leads to a strong and long-lasting immune response with memory. They can even induce mucosal immunity when given through certain routes, but they carry a small risk to people with weakened immune systems and, rarely, can revert to a harmful form; they also tend to require careful storage.

Killed vaccines use pathogens that have been inactivated and cannot replicate. They still provoke an immune response, but typically not as robust or durable as live vaccines, so they usually require additional doses and sometimes adjuvants to boost protection. They are generally safer for immunocompromised individuals and do not carry a risk of reversion to virulence, though they don’t stimulate as strong a cellular response as living vaccines.