Health

How do inactivated vaccines protect the body? – VnExpress


Inactivated vaccines are one of the commonly used vaccines today with many properties to help protect the body against pathogens.

What is an inactivated vaccine?

Inactivated vaccines are produced by culturing pathogens, usually viruses, in suitable media. When they are fully grown, heat, chemicals, or radiation are used to destroy the genetic material and “kill” the pathogens.

Pathogens are inactivated by heat, chemicals or radiation. Photo: Fraunhofer IZI

Even though the genetic material has been destroyed, the pathogen still contains many components capable of triggering an immune response. When entering the body, antigens from pathogens will be recognized by antigen-presenting cells (APCs) and transported to the lymph nodes. During transport, pathogens are broken down by enzymes into peptide fragments, called epitopes. These epitopes will bind to the MHC molecule to form a peptide-MHC complex on the cell surface.

This complex is then recognized by T-cells in the lymph nodes by T-cell receptors, thereby stimulating an antigen-specific immune response, either antibody-mediated or cell-mediated. This process creates an “immune memory” that helps the body fight off a particular pathogen, and also allows the immune system to respond more quickly and efficiently when exposed to that pathogen in the future.

Pros and cons of inactivated vaccines

In general, each type of vaccine has its own advantages and disadvantages. Compared with live attenuated vaccines (vaccines containing live but attenuated pathogens), the protective efficacy of inactivated vaccines is usually less effective. This is because the inactivated vaccine only stimulates an antibody-mediated immune response, so the response will be weak and short-lived. This is also the reason why inactivated vaccines need 3 to 4 booster doses for optimal protection, while live attenuated vaccines only need 1-2 doses.

In addition, the production of inactivated vaccines requires standard facilities and laboratories to safely culture bacteria and viruses, and requires a relatively longer time compared to other vaccines. .

In contrast, inactivated vaccines also bring many outstanding advantages. First, because the pathogen in the vaccine is already dead, the storage conditions of the inactivated vaccine will not be as strict as that of a live attenuated vaccine. This helps the vaccine to be transported to difficult areas where modern preservation equipment is not available.

Second, inactivated vaccines are pathogens that have died or are completely inactivated, so they cannot replicate and return to the active form to cause disease. Therefore, they will be suitable for many people, including people with compromised immune systems.

Common inactivated vaccines

There are many vaccines researched and developed using this technology such as: hepatitis A vaccine, influenza vaccine (injection route), polio vaccine (injection route), rabies vaccine, pertussis vaccine.

Hepatitis A vaccine can be made by inactivating the pathogen.  Photo: CPhI Online

Hepatitis A vaccine can be made by inactivating the pathogen. Photo: CPhI Online

Inactivated vaccine technology is also being widely applied in research and development of vaccines against Covid-19. Verocell and Hayat – Vax are two vaccines against Covid-19 that are made by inactivating corona virus.

Phuong Quynh

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