Inactivated vaccine
| Inactivated vaccine | |
|---|---|
infectious diseases | |
| Frequency | birth to adulthood |
| Outcomes | development of active immunity in individuals; contribution to herd immunity |
An inactivated vaccine (or killed vaccine) is a vaccine consisting of virus particles, bacteria, or other pathogens that have been grown in culture and then killed to destroy disease-producing capacity. In contrast, live vaccines use pathogens that are still alive (but are almost always attenuated, that is, weakened). Pathogens for inactivated vaccines are grown under controlled conditions and are killed as a means to reduce infectivity and thus prevent infection from the vaccine.[1]
Inactivated vaccines were first developed in the late 1800s and early 1900s for cholera, plague, and typhoid.[2] Today, inactivated vaccines exist for many pathogens, including influenza, polio (IPV), rabies, hepatitis A and pertussis.[3]
Because inactivated pathogens tend to produce a weaker response by the immune system than live pathogens,
Mechanism
The pathogen particles are destroyed and cannot divide, but the pathogens maintain some of their integrity to be recognized by the immune system and evoke an adaptive immune response.[6][7] When manufactured correctly, the vaccine is not infectious, but improper inactivation can result in intact and infectious particles.[citation needed]
When a vaccine is administered, the antigen will be taken up by an antigen-presenting cell (APC) and transported to a draining lymph node in vaccinated people. The APC will place a piece of the antigen, an epitope, on its surface along with a major histocompatibility complex (MHC) molecule. It can now interact with and activate T cells. The resulting helper T cells will then stimulate an antibody-mediated or cell-mediated immune response and develop an antigen-specific adaptive response.[8][9] This process creates an immunological memory against the specific pathogen and allows the immune system to respond more effectively and rapidly after subsequent encounters with that pathogen.[6][8][9]
Inactivated vaccines tend to produce an immune response that is primarily antibody-mediated.[3][10] However, deliberate adjuvant selection allows inactivated vaccines to stimulate a more robust cell-mediated immune response.[1][7]
Types
Inactivated vaccines can be divided by the method used for killing the pathogen.[4][1]
- Whole pathogen inactivated vaccines are produced when an entire pathogen is 'killed' using heat, chemicals, or radiation,
- Split virus vaccines are produced by using a detergent to disrupt the viral envelope.[4][13] This technique is used in the development of many influenza vaccines.[14]
A minority of sources use the term inactivated vaccines to broadly refer to non-live vaccines. Under this definition, inactivated vaccines also include subunit vaccines and toxoid vaccines.[3][8]
Examples
Types include:[15]
- Viral:
- Injected Salk vaccine)
- Hepatitis A vaccine
- Rabies vaccine
- Most influenza vaccines
- Tick-borne encephalitis vaccine
- Some TURKOVAC, CoviVac
- Injected
- Bacterial:
- Injected typhoid vaccine
- Cholera vaccine
- Plague vaccine
- Whole-cell Pertussis vaccine
Advantages and disadvantages
Advantages
- Inactivated pathogens are more stable than live pathogens. Increased stability facilitates the storage and transport of inactivated vaccines.[8][16][17]
- Unlike live attenuated vaccines, inactivated vaccines cannot revert to a virulent form and cause disease.[6][10] For example, there have been rare instances of the live attenuated form of poliovirus present in the oral polio vaccine (OPV) becoming virulent, leading to the inactivated polio vaccine (IPV) replacing OPV in many countries with controlled wild-type polio transmission.[6][9]
- Unlike live attenuated vaccines, inactivated vaccines do not replicate and are not contraindicated for immunocompromised individuals.[6][7][8]
Disadvantages
- Inactivated vaccines have a reduced ability to produce a robust immune response for long-lasting immunity when compared to live attenuated vaccines.[3] Adjuvants and boosters are often required to produce and maintain protective immunity.[10][16]
- Pathogens must be cultured and inactivated for the creation of killed whole-organism vaccines.[6][9] This process slows down vaccine production when compared to genetic vaccines.[8]
References
- ^ S2CID 154670.
- S2CID 32506969.
- ^ a b c d Wodi AP, Morelli V (2021). "Chapter 1: Principles of Vaccination" (PDF). In Hall E, Wodi AP, Hamborsky J, Morelli V, Schilllie S (eds.). Epidemiology and Prevention of Vaccine-Preventable Diseases (14th ed.). Washington, D.C.: Public Health Foundation, Centers for Disease Control and Prevention.
- ^ a b c WHO Expert Committee on Biological Standardization (19 June 2019). "Influenza". World Health Organization (WHO). Retrieved 22 October 2021.
- ^ a b "Types of Vaccines". Vaccines.gov. U.S. Department of Health and Human Services. 23 July 2013. Archived from the original on 9 June 2013. Retrieved 16 May 2016.
- ^ S2CID 25514266.
- ^ PMID 24709587.
- ^ PMID 33353987.
- ^ PMID 27157411.
- ^ OCLC 989157433.
- S2CID 81212732.
- S2CID 238747462. Retrieved 14 April 2022.
- PMID 34326849.
- )
- ^ Ghaffar A, Haqqi T. "Immunization". Immunology. The Board of Trustees of the University of South Carolina. Archived from the original on 26 February 2014. Retrieved 2009-03-10.
- ^ PMID 21572612.
- ^ "Inactivated whole-cell (killed antigen) vaccines - WHO Vaccine Safety Basics". vaccine-safety-training.org. World Health Organization (WHO). Retrieved 2021-11-11.