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What are the different types of vaccines?

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Historically, there are four main types of vaccines:  - Live-attenuated vaccines - Inactivated vaccines - Subunit, recombinant, polysaccharide, and conjugate vaccines - Toxoid vaccines Vaccine designs are based on how our immune systems respond to germs, who in the population (children, adults) needs to be vaccinated against the germ, and the best approach and technology available to create the vaccine. This is why there are different vaccine types to respond to different germs. Live-attenuated vaccines use a weaker - also called 'attenuated' - form of a living germ, which would normally cause a disease in stronger forms but is almost completely harmless in a vaccine because the virus has been weakened. Some of these live-attenuated vaccines are used to protect against diseases like measles, mumps, rubella; rotavirus; smallpox; chicken pox; and yellow fever. Inactivated vaccines use the killed or inactive version of the germ, so they are not as capable at helping humans develop some immunity to a germ** **as live-attenuated vaccines and can't provide immunity for as long. These vaccines protect against diseases like hepatitis A, influenza, polio, and rabies. Subunit, recombinant, polysaccharide, and conjugate vaccines use particular pieces of the germ, like its protein or sugars, to create a strong immunity to specific parts of the germ. Some illnesses these vaccines focus on are hepatitis B, HPV, whooping cough, shingles, and meningococcal disease. Toxoid vaccines use a harmful product called a 'toxin' that is made by the germ. A toxin is a living organism that can normally cause harm to parts of the body like tissues when they come into contact with them. However, toxins in vaccines are harmless because they have been very weakened in laboratories as their only job is to teach the immune system how to fight the germ. They create immunity by focusing on the specific parts of the germ that cause illness instead of the entire germ. These vaccines target illnesses like diptheria and tetanus. Researchers trying to develop COVID-19 vaccines are using many of these types of approaches to vaccine design. Two new types of vaccines are gaining attention in the scientific world. One of these vaccine types use the genes of the COVID-19 vaccine called 'DNA' and 'RNA' to create a strong immune system response. The other new type of approach to vaccine development uses a platform base called 'recombinant vector vaccines' which act like how infections would impact your body normally. As we learn more about the virus and how to create immunity in people through vaccines, we will learn if any of these vaccine types can successfully prevent COVID-19 infection in people.

This article was published on
July 31, 2020

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What our experts say

Historically, there are four main types of vaccines: 

  • Live-attenuated vaccines
  • Inactivated vaccines
  • Subunit, recombinant, polysaccharide, and conjugate vaccines
  • Toxoid vaccines

Vaccine designs are based on how our immune systems respond to germs, who in the population (children, adults) needs to be vaccinated against the germ, and the best approach and technology available to create the vaccine. This is why there are different vaccine types to respond to different germs.

Live-attenuated vaccines use a weaker - also called 'attenuated' - form of a living germ, which would normally cause a disease in stronger forms but is almost completely harmless in a vaccine because the virus has been weakened. Some of these live-attenuated vaccines are used to protect against diseases like measles, mumps, rubella; rotavirus; smallpox; chicken pox; and yellow fever.

Inactivated vaccines use the killed or inactive version of the germ, so they are not as capable at helping humans develop some immunity to a germ as live-attenuated vaccines and can't provide immunity for as long. These vaccines protect against diseases like hepatitis A, influenza, polio, and rabies.

Subunit, recombinant, polysaccharide, and conjugate vaccines use particular pieces of the germ, like its protein or sugars, to create a strong immunity to specific parts of the germ. Some illnesses these vaccines focus on are hepatitis B, HPV, whooping cough, shingles, and meningococcal disease.

Toxoid vaccines use a harmful product called a 'toxin' that is made by the germ. A toxin is a living organism that can normally cause harm to parts of the body like tissues when they come into contact with them. However, toxins in vaccines are harmless because they have been very weakened in laboratories as their only job is to teach the immune system how to fight the germ. They create immunity by focusing on the specific parts of the germ that cause illness instead of the entire germ. These vaccines target illnesses like diptheria and tetanus.

Researchers trying to develop COVID-19 vaccines are using many of these types of approaches to vaccine design. Two new types of vaccines are gaining attention in the scientific world. One of these vaccine types use the genes of the COVID-19 vaccine called 'DNA' and 'RNA' to create a strong immune system response. The other new type of approach to vaccine development uses a platform base called 'recombinant vector vaccines' which act like how infections would impact your body normally. As we learn more about the virus and how to create immunity in people through vaccines, we will learn if any of these vaccine types can successfully prevent COVID-19 infection in people.

Context and background

There are over 165 vaccines against COVID-19 in development around the world. Approximately 25 of them are in human trials. Vaccine trials typically take years to develop, but are being expedited to be ready as early as spring 2021 to control the pandemic. 

Vaccines are a safe, effective, and simple method of protecting people against diseases before an individual becomes exposed to them. Vaccines can also help lessen the severity of a disease if someone is infected. All vaccines work to create antibodies to fight the foreign germ - in this case, the SARS-CoV-2 virus. But there has been confusion around the types of vaccines in development due to the high amount of vaccines being developed, as well as new technologies being tested that haven’t been used in a licensed vaccine before, such as mRNA vaccines which are currently being researched.

Resources

  1. Vaccine Types (U.S. HHS)
  2. Vaccines: The Basics (U.S. CDC)
  3. Q&A on vaccines (World Health Organization)

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