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What are the Different Types of Vaccines?

There are different types of vaccines and their primary components determine how they are administered, how they are used, and how they are stored. Having an idea of how each vaccine works helps keep them safe and effective. Since they are designed to work differently, you need to be aware of special considerations that need to be taken when administering the vaccine to immunocompromised patients and pregnant women. This article will be looking at the different types of vaccines including the components used, how they work, and the contraindications that may present an additional risk when administering the vaccines.

  • Live Attenuated Vaccines (LAV)

This type of vaccine is derived from a live virus or bacteria that have been attenuated or weakened under laboratory conditions. They cause no disease since they are weak and they will continue to grow in a vaccinated individual, they replicate within host cells thus providing a strong immunity against viruses or intracellular microorganisms. Some examples of live attenuated vaccines recommended by the World Health Organization (WHO) include Varicella (chickenpox), Tuberculosis (BCG), Rotavirus, and the Oral polio vaccine.

It is very rare for attenuated pathogens to revert to a pathogenic form once it has been administered to an individual. However, live attenuated vaccines have raised some safety concerns in the health community because they contain living organisms. Although the disease-causing pathogens have already been weakened, there is a higher degree of unpredictability that may result in immunization errors.

  • Inactivated Vaccines

This type of vaccine is derived from disease-causing pathogens that have been destroyed through chemical or physical processes. Since inactivated vaccines do not have any living organisms, they do not have the potential of causing disease. Unlike live attenuated vaccines, inactivated vaccines may not induce a strong immune response. Some examples of inactivated vaccines include inactivated polio vaccine (IPV) and Whole-cell pertussis vaccine (wP).  Generally, inactivated vaccines are considered more stable than the LAVs the fact that they have no living components. However, the response is always short-lived and you may be injected with several doses of an inactivated vaccine to evoke a sufficient immune response.

  • Subunit Vaccines

Just like inactivated whole-cell vaccines, subunit vaccines do not contain any live virus or bacteria. The primary difference between these two types of vaccines is that subunit vaccines only contain the antigenic components of the pathogen, which elicit a protective immune response. However, the antigenic properties of individual potential subunits of a pathogen are examined in detail to find out the particular combinations that elicit an effective immune response in the correct pathway. Although an immune response may be evoked, there is no guarantee that the immunological memory will be established correctly. The benefit of using subunit vaccines is that they don’t contain any live pathogens so they have no risk of inducing the disease, making them safer and more stable than the live attenuated vaccines. Some examples of subunit vaccines include Hepatitis B vaccine (HepB) and Acellular pertussis vaccine (Ap).

  • Toxoid Vaccines

Toxoid vaccines are derived from the type of toxin produced by certain bacteria such as diphtheria and tetanus. The toxin is significantly responsible for the symptoms of the disease and invades the bloodstream of the affected individual. Toxoid is a protein-based toxin that is rendered harmless and elicits an immune response because it is used as the antigen in the vaccine. It is usually adsorbed to calcium and aluminum salts which serve as adjuvants that increase the immune response.

Unlike other types of vaccines, the toxoid vaccine is not highly immunogenic as you may require several doses and is often accompanied by an adjuvant. In terms of safety and stability, toxoid vaccines cannot cause the disease it prevents and there are very rare systemic and local reactions. Some examples of toxoid vaccines include Tetanus toxoid (TT), and Diphtheria toxoid (Dt and Td). Generally, Toxoid vaccines are usually stable and long lasting compared to the LAVs.

  • Combined Vaccines

Combination vaccines are subjected to extensive testing before the national regulatory authorities can approve them. This helps to ensure that the products are effective, safe, and of acceptable quality. Combination vaccines are made up of two or more antigens integrated into the same preparation. Some examples of the combined vaccine include DTwP and the MMR vaccine for measles, mumps, and rubella. The potential advantage of combined vaccines is that they reduce the cost of administering separate vaccines, which improves the timeliness of vaccination.

New types of vaccines are being developed every year by scientific researchers who seek to improve the current approaches used to formulate a vaccine. Each type of vaccine comes with its benefits and downsides. It is important to talk to your doctor about the side effects of a vaccine to know which type of vaccine works best for you.

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