English Reference

Word

immunization

Phoneticsim·mu·niza·tion

/ˌɪmjunəˈzeɪʃən/

UK spelling · immunisation

Definitions

01the medical process

B2 · Medicine

n. the process of making someone immune to a disease, usually by using a vaccine to help the body learn how to fight it.

n. the physiological process of inducing immunity, typically through the administration of an immunogen to stimulate a primary immune response.

“Mass immunization programs have helped to eliminate many dangerous diseases around the world.”

“Public health officials emphasized that widespread immunization is the most effective strategy for achieving herd immunity within the local population.”

Technical

Usage

Often used as an uncountable noun when referring to the general medical practice or biological process.

Synonyms

vaccinationinoculation

02a specific treatment

B2 · Medicine

n. a specific instance of being given a vaccine; a shot or treatment.

n. a specific instance or dose of an immunizing agent administered to a patient.

“The school requires all new students to show proof of their childhood immunizations.”

“The clinic provides a schedule of required immunizations for infants to ensure they are protected against common respiratory infections.”

American English

Usage

Commonly used as a countable noun in American English, where 'vaccination' might be preferred in British English.

Teaching tip

In American English, 'immunization' and 'vaccination' are often used interchangeably in clinical settings, though 'immunization' technically refers to the result.

Real-World Examples

“While measles was declared eliminated from the US in 2000, cases are now increasing: in August, approximately 2,465 cases were confirmed, a rise linked to slumping immunization rates.”
The Guardian · 13 Aug 2026
“The MenB vaccine was added to the UK NHS childhood immunisation programme for babies born on or after 1 July 2015.”
BBC News · 3 Aug 2026

Etymology

From French immunisation. Coined by Albert Calmette. Equivalent to immunize + -ation or immune + -ization.

Etymology adapted from Wiktionary, available under CC BY-SA 4.0.

This entry

Level
B2 · Upper Intermediate
Frequency
Occasional
Updated

Scan code

englishreference.com/q/immunization

English Reference