What is the Difference Between Live Attenuated and Inactivated Vaccines?

Live attenuated vaccines and inactivated vaccines are two different types of vaccines used to protect against various diseases. The main differences between them are:

1. Virus Strength: Live attenuated vaccines use a weakened (attenuated) form of the virus, while inactivated vaccines are made from a protein or other small pieces taken from a virus or bacteria.
2. Immune Response: The immune response to a live attenuated vaccine is virtually identical to that produced by a natural infection because the immune system does not differentiate between an infection with a weakened vaccine virus and an infection with a wild virus. Inactivated vaccines, on the other hand, do not produce the same level of immune response as a live attenuated vaccine.
3. Number of Doses: Live attenuated vaccines, such as the measles, mumps, and rubella (MMR) vaccine, usually produce immunity in most recipients with one dose. Inactivated vaccines may require multiple doses to provide adequate protection.
4. Safety: Live attenuated vaccines are generally considered safe for most people. However, they should not be given to people with weakened immune systems or pregnant women, as they may be dangerous in these cases. Inactivated vaccines are considered safer for people with weakened immune systems.

Examples of live attenuated vaccines include the MMR vaccine and the varicella (chickenpox) vaccine. Examples of inactivated vaccines include the whooping cough (pertussis) vaccine and the influenza vaccine (nasal spray version).

Comparative Table: Live Attenuated vs Inactivated Vaccines

Here is a table comparing live attenuated and inactivated vaccines:

Live attenuated vaccines contain weakened or attenuated pathogens, stimulating a strong and effective immune response. They often provide lifelong immunity with a single dose. Examples include measles, mumps, and chickenpox vaccines.

Inactivated vaccines contain killed or altered pathogens, stimulating a weaker and less effective immune response. They usually require multiple doses and may need boosters for continued protection. Examples include BCG vaccine for tuberculosis and typhoid vaccine.