Vaccine versus immunize, and immunization versus vaccination. (You say, “tomato,” and I say, “tomahto.”)

Many people use the words interchangeably even though they mean slightly different things. We thought you might want to know that we know that.

Vaccine: A preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease.

Immunize: To give (someone) a vaccine to prevent infection by a disease.

Vaccination: When a person is given something to make the immune system learn to fight an infectious disease.

Immunization: When a person’s immune system learns to fight an infection. Immunization can happen from vaccination. But immunization can also happen from getting the infection.

Efficacy: The ability to produce a desired or intended result.

Antigen: Any substance that causes the immune system to produce antibodies against it. Antigens include foreign substances (chemicals, virus, pollen, bacteria) or toxins within the body (bacteria toxins, tissue).

Pathogen: An agent that causes disease, such as a living microorganism (i.e. bacteria).

Antibody: Y-shaped proteins on the surface of B-cells that are secreted into blood in response to an antigenic stimulus that neutralizes the antigen by binding to it.

Effective: In the vaccine world this means how well does it protect a certain percent of the population.

Morbidity: The rate illness associated with a disease. It refers to an incidence of ill health in a population.

Mortality: The death associated with a disease. It refers to the incidence of death or the number of deaths in a population. People will often misuse mortality data. Keep in mind that it is very difficult to compare mortality rates across countries.