Types of Immunization

Immunization is a method of creating immunity or protection against certain illnesses and diseases. It is accomplished by introducing small amounts of a weakened or killed disease-causing virus or bacteria. Upon introduction of the pathogen, the immune system reacts by fighting off the “infection” and producing antibodies that fight the germ if it re-enters the body in the future.

Types of Vaccine

Vaccines come in several different forms with each type designed to bolster the immune system’s response to certain germs and the diseases they lead to.

When creating vaccines, scientists consider:
* How the immune system will respond to the pathogen
* Who should be vaccinated against the pathogen
* The ideal approach or technology to create a vaccine

Scientists will determine the type of vaccine to make based on these factors. Vaccines come in several different types, including:
* Inactivated vaccines
* Live-attenuated vaccines
* Messenger RNA vaccines (mRNA)
* Polysaccharide, conjugate, recombinant, and subunit vaccines
* Toxoid vaccines
* Viral vector vaccines

Inactivated Vaccines

This type of vaccine relies on killed versions of the pathogen that leads to a certain disease. In general, inactivated vaccines do not provide immunity that is as strong as that of live vaccines. As such, patients may require multiple doses (booster shots) over the years to build ongoing immunity against the disease.
Among the diseases that inactivated vaccines are made to guard against include:

* Hepatitis A
* Influenza
* Polio
* Rabies

Live-Attenuated Vaccines

Vaccines of this type utilize weakened (attenuated) forms of a pathogen. Since these vaccines are quite similar to that of a natural infection, they create stronger and longer-lasting immune system responses. Most live vaccines provide lifetime protection against a disease through one or two doses.
Live-attenuated vaccines help guard against:
* Measles, mumps, and rubella
* Rotavirus
* Smallpox
* Chickenpox
* Yellow fever

Messenger RNA Vaccines (mRNA)

Recently developed for use in some COVID-19 vaccines, mRNA vaccines have been researched and worked with for decades. mRNA vaccines create proteins to stimulate an immune system reaction. Compared to other vaccine types, mRNA has the benefit of reduced manufacturing time and since they have no live virus within them, do not run the risk of causing disease in the vaccinated person.

Polysaccharide, Conjugate, Recombinant, and Subunit Vaccines

These vaccines utilize specific parts of a pathogen such as its sugar, protein, or capsid (casing around a pathogen). By utilizing specific parts of the germ, these vaccines produce a strong immune reaction. Furthermore, they can be utilized by virtually anyone, including those with long-term health issues or weak immune systems.

Diseases that these vaccines offer protection from include:
* Hib disease
* Hepatitis B
* Human Papillomavirus
* Whooping Cough

Toxoid Vaccines

Relying on a toxin produced by the pathogen, these vaccines create immunity against the parts of the pathogen that cause disease rather than the pathogen itself. As such, the immune system reaction targets the toxin rather than the whole pathogen.
Toxoid vaccines help protect patients from:
* Diptheria
* Tetanus

Viral Vector Vaccines

These vaccines utilize modified versions of a different virus (a vector) to build immunity. Amongst the viruses used as vectors include measles, influenza, vesicular stomatitis, and adenovirus. Viral vector vaccines have been used to combat HIV, Zika, influenza, and COVID-19.

What is Immunization