Difference Between Live Attenuated and Inactivated Vaccines

The key difference between live attenuated and inactivated vaccines is that live attenuated vaccines are vaccines that contain pathogens that have been weakened or attenuated, while inactivated vaccines are vaccines that contain pathogens that have been killed or have been altered.

Live attenuated and inactivated vaccines are two types of vaccines used in the process of vaccination. Vaccination is a simple and safe way of protecting people from various harmful diseases especially bacterial and viral infections. Vaccines protect people from pathogens that come into contact with them. Generally, vaccines stimulate the immune system to create antibodies when the body is exposed to a disease. However, the vaccines contain a weakened or killed form of germs such as bacteria or viruses. Therefore, they do not put people at risk after usage.

CONTENTS

1. Overview and Key Difference
2. What are Live Attenuated Vaccines
3. What are Inactivated Vaccines
4. Similarities Between Live Attenuated and Inactivated Vaccines
5. Side by Side Comparison – Live Attenuated vs Inactivated Vaccines in Tabular Form
6. Summary

What are Live Attenuated Vaccines?

Live attenuated vaccines are vaccines that contain pathogens (bacteria, viruses) that have been weakened (attenuated). An attenuated vaccine is created by reducing the virulence of a pathogen. But in an attenuated vaccine, the pathogen is still viable. In the process of attenuation, infectious agents are altered to make them less virulent. These vaccines are different from inactivated vaccines that are produced by killing the pathogen.

Attenuated vaccines trigger a strong immune response that is long-lasting. Moreover, attenuated vaccines produce a stronger and more durable immune response with a quick immunity onset. The function of an attenuated vaccine is to encourage the body to create antibodies and memory cells in response to a specific pathogen such as bacteria and viruses. The common examples of attenuated vaccines include mumps, rubella, yellow fever, and some influenza vaccines. Attenuated vaccines can be administrated in various ways: injections (subcutaneous and intradermal) or mucosal (nasal or oral). Compared to inactivated vaccines, live-attenuated vaccines are more prone to immunization errors.

What are Inactivated Vaccines?

Inactivated vaccines are vaccines that contain pathogens (bacteria, viruses, fungi) that have been killed or have been altered. An inactivated vaccine or killed vaccine is a vaccine consisting of viruses, bacteria or other pathogens that have been killed to destroy its disease-producing capacity. Pathogens for inactivated vaccines grow under controlled conditions. Then they are killed to reduce infectivity thus, preventing the infection from the vaccine. Viruses are killed by using heat or formaldehyde. Moreover, viruses, bacteria and fungi are also inactivated by using gentle poring methods. Though inactivated vaccine encourages the body to create antibodies, the immune response is much slower than attenuated vaccines.

Inactivated vaccines can be further classified depending on the method used to inactivate pathogens, such as ghost vaccines (bacterial ghosts), whole virus vaccines, split virus vaccines, and subunit vaccines. Inactivated vaccines provide better protection for the elderly and immunocompromised people.

What are the Similarities Between Live Attenuated and Inactivated Vaccines?

• Both vaccines use pathogens such as bacteria and viruses.
• They provide immunization to human against harmful diseases.
• These vaccines trigger antibody production through the immune system.
• They are both approved by World Health Organization (WHO) for the vaccination process.

What is the Difference Between Live Attenuated and Inactivated Vaccines?

Live attenuated vaccines are vaccines that contain pathogens that have been weakened or have been attenuated. In contrast, inactivated vaccines are vaccines that contain pathogens that have been killed or have been altered. So, this is the key difference between live attenuated and inactivated vaccines. Moreover, live attenuated vaccines stimulate a strong and effective immune response, while inactivated vaccines stimulate a weaker and less effective immune response.

Below is a list of differences between live attenuated and inactivated vaccines in tabular form for side by side comparison.

Summary – Live Attenuated vs Inactivated Vaccines

A vaccine is a biological preparation that provides active acquired immunity to a particular infectious disease. A vaccine normally contains a biological agent that resembles a disease-causing microorganism. It is usually made from weakened or killed forms of the microbe, its toxins, or one of its surface proteins. Vaccines stimulate the immune system to create antibodies when the body is exposed to a disease. Live attenuated and inactivated vaccines are two types of vaccines. Live attenuated vaccines contain pathogens that have been weakened or have been attenuated. Inactivated vaccines contain pathogens that have been killed or have been altered. Thus, this is the summary of the difference between live attenuated and inactivated vaccines.

Reference:

1. “LIVE ATTENUATED VACCINES (LAV).” Vaccine Safety Basics, Available here.
2. “Inactivated Vaccine.” An Overview | ScienceDirect Topics, Available here.

Image Courtesy:

1. “MMR vaccine” By Whispyhistory – Own work (CC BY-SA 4.0) via Commons Wikimedia
2. “COVID-19 vaccine” By Alachua County (Public Domain) via Flickr