Types of Vaccines

1. Does the vaccine recipient have any immunocompromising conditions, or have they taken any medications in the past three months that cause immunosuppression, including corticosteroids?

2. If giving a live vaccine to young child (note: live vaccines are not given to infants (<12 months of age), consider:

• Is there a known or suspected family history of congenital immunodeficiency disorder, HIV infection, or a history of failure to thrive AND recurrent serious infections?

3. Has the vaccine recipient received any other live vaccines in the past four weeks?

4. Has the vaccine recipient received any transfusions of blood or blood products in the last year?

Inactivated/Killed Vaccines

Inactivated vaccines, sometimes referred to as killed vaccines, are composed of either whole or partial pathogens that are not alive and therefore cannot replicate. Pathogens become inactivated through exposure to heat, chemicals, and other purification processes. These types of vaccines prevent diseases caused by bacteria and viruses.

In this case, inactivated/killed vaccines refer to whole pathogen vaccines. Inactivated vaccines use the killed version of the pathogen and its antigens to induce an immune response. Typically, these vaccines provide immune protection that is not as effective as live-attenuated vaccines and often require multiple doses over time in order to sustain immunity as the antibody titers diminish. Generally, the first dose of an inactivated vaccine serves to prime the immune system, while protective immunity (antibody) is provided after the second or third dose. Inactivated vaccines are safer for use in immunocompromised individuals since the vaccine contains inactivated or killed pathogens.

Toxoid (inactivated toxin) Vaccines

Toxoid vaccines are used to prevent diseases caused by bacteria. The vaccine uses a toxin (rendered harmless) made by the pathogen that causes the disease. As a result, the body produces an immune response targeted to the toxin rather than the pathogen itself. It is important to note that toxins are typically responsible for symptoms of a disease, such that exposure to the toxin can elicit immunity.

Toxoid vaccines are safe because they cannot cause the disease. Toxoid vaccines typically require booster vaccinations to sustain immunity.

Subunit Vaccines: Recombinant, Polysaccharide and Conjugate Vaccines

Subunit vaccines use a piece of the pathogen, such as its protein, sugar, or capsid, to provoke an immune response. These vaccines elicit a strong and targeted response to a part of the pathogen and are typically suitable for anyone, including immunocompromised individuals. For sustained immunity, clients typically need multiple doses of vaccine.

While recombinant, polysaccharide, and conjugate are all forms of subunit inactivated vaccines, each target a particular molecular structure. Polysaccharide vaccines consist of long-chained sugar molecules attached to the surface of bacteria such as pneumococcus and meningococcus. Recombinant vaccines are genetically engineered vaccines, whereby pathogenic agents have been cloned, expressed, and purified into a vaccine.

There are several different types of vaccines available, each with a different set of properties and uses. Scientific advances and new technology will continue to change and improve the vaccine landscape. Table 1.1. offers examples of some of the vaccines associated with the various vaccine types.

Attribution Statement

Content in this section was adapted, with editorial changes, from Page 8: Canadian Immunization Guide: Part 1 – Key Immunization Information by the Government of Canada and is reproduced under non-commercial conditions.

Content in Table 1.1 was adapted, with editorial changes, from https://www.vaccines.gov, which is in the public domain.