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Types of Ingredients:

  • Active ingredients: the substances that trigger your immune system to make antibodies. These ingredients are often derived from the pathogen itself. There are multiple types of active ingredients depending on the type of vaccine

  • Adjuvants: a compound added to some vaccines to strengthen the immune response

  • Antibiotics: substances that kill bacteria or prevent them from dividing. Antibiotics are used in some vaccines to prevent contamination during the manufacturing process

  • Carbohydrates: This is another word for sugar. Carbohydrates are normally used as stabilizers in vaccines

  • Lipids: substances that do not mix with water such as fats, hormones, waxes, and oils

  • Salts: a type of compound that can act as electrolytes, which are charged substances that help to maintain the pH and fluid balance in the body so that the organs can function properly. Some common examples of electrolytes are sodium (Na+), potassium (K+), and chloride (Cl-). NaCl (table salt) is a common example of a salt.

Types of Vaccines

Attenuated Vaccines: 

Contain a weakened version of the bacterium or virus that is unable to cause disease in healthy people. These vaccines tend to be very effective at creating a strong immune response 

Some examples of attenuated vaccines include the measles, mumps, and rubella (MMR) combined vaccine, the rotavirus vaccines, the nasal flu vaccine (flumist), and the chickenpox vaccine.

Inactive Vaccines: 

Contain a version of the whole bacterium or virus that is dead or cannot replicate. This type of vaccine cannot cause disease even in people with very weak immune systems. 

Some examples of inactive vaccines are the hepatitis A, influenza (flu), and polio (IPV) vaccines.

Subunit Vaccines:

Made to create an immune response to a specific piece of a bacterium or virus such as a protein or sugar. Subunit vaccines create a strong immune response and are very safe because they only contain a small piece of the pathogen, which means that it cannot replicate or cause disease. 


There are multiple types of subunit vaccines:

  • Recombinant Protein Vaccines: Recombinant proteins are made by putting genetic information into the genome of another species (often bacteria or yeast). That species makes the protein, which is isolated and purified. The purified protein is used as an antigen in vaccines. 

    • Recombinant proteins are made with the same technology used to make insulin​ — for a great explanation of this process, click here

  • Toxoid Vaccines: a toxoid is an inactive version of a toxin produced by a bacterium. The body is able to make antitoxin without being exposed to the actual toxin. Toxoids are not toxic. 

  • Conjugate VaccinesA type of vaccine that attaches an antigen (often a sugar) to a protein in order to improve the protection the vaccine provides.

  • Outer Membrane Vesicle (OMV) Vaccines: OMVs are a piece of the cell membrane from a bacterium that split off from the rest of the cell. These vesicles are naturally produced by bacteria, but are not infectious because they contain no genetic material and cannot replicate. OMVs contain surface antigens that the immune system can use to produce antibodies.

Subunit vaccines are the most common type of vaccine. Examples of subunit vaccines include hepatitis B, HPV, meningococcal, meningococcal B, Haemophilus influenzae type B (Hib), pneumococcal, tetanus, diphtheria, and pertussis.

Nucleic Acid Vaccines:

mRNA is a type of genetic information that is used to make a protein. In nucleic acid vaccines, mRNA is the active ingredient. The body uses the mRNA as instructions to make a bacterial or viral protein, which acts as an antigen. The mRNA and protein are harmless on their own. The immune system responds to this protein by creating antibodies. The mRNA encodes a protein that teaches your body how to respond if it is exposed to the virus in the future.
Some examples of nucleic acid vaccines are the Pfizer and Moderna COVID-19 vaccine.

Viral Vector Vaccines:

Viral vector vaccines also deliver genetic information to the body in order to make a protein. Genetic information encoding a protein is inserted into the genome of a different virus that is harmless. This harmless, modified virus is used as the active ingredient, and the body uses this genetic information to make a bacterial or viral protein. This protein acts as an antigen, and the immune system responds to this protein by creating antibodies, which teach your body how to respond if it is exposed to the virus in the future. Some examples of viral vector vaccines are the Johnson & Johnson and Novavax COVID-19 vaccines.

For a good explanation of these vaccines, click here.

Relevant Terms

  • Antibody: a protein made by the immune system in response to a foreign particle (antigen). These proteins circulate in the blood and help defend the body against the substance.  

  • Antigen: This is any substance that triggers the immune system to create antibodies. For example, allergens such as pollen are antigens. 

  • Bacterium: the singular of bacteria (one bacterium, two bacteria)

  • Genome: all of the genetic information in a cell

  • mRNA: Messenger ribonucleic acid (mRNA) is a form of genetic material that acts as a template to make proteins through a process called translation. Learn more about translation here

  • Pathogen: a microscopic organism that can cause disease (usually a bacterium or virus)

  • pH: a measure of how acidic or basic a solution is. The scale ranges from 0 (very acidic) to 14 (very basic). A pH of 7 is neutral.

  • Quadrivalent: Protects against four different versions of the pathogen (in this case, influenza virus)

  • Recombinant Protein: a protein that is made by putting genetic information into the genome of another species. That species makes the protein, which is isolated and purified. 

  • Viral vector: a version of a virus that cannot replicate or cause disease. It is used to deliver genetic information so that the body can make a protein that acts as an antigen.

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