Infection vs Virus

When to use each in English, with meaning, register, and examples.

Infection

Top 1,000 (very common) B2 noun

Virus

Top 1,000 (very common) A2 noun

	Infection	Virus
Pronunciation	🇬🇧 /["/ɪnˈfekʃn/"]/ 🇺🇸 /["/ɪnˈfekʃn/"]/	🇬🇧 /["/ˈvaɪrəs/"]/ 🇺🇸 /["/ˈvaɪrəs/"]/
Meaning	When germs or bacteria get into the body and make you sick.	A tiny living thing that can make you sick.
Example	The doctor confirmed that the patient had a bacterial infection in his lungs.	The doctor explained how a virus can spread from one person to another.
Register	Neutral	Neutral
How common	Top 1,000 (very common)	Top 1,000 (very common)
CEFR level	B2	A2
Part of speech	noun	noun
Collocations	nasty, serious, severe, have, suffer, suffer from, develop, occur, spread, in infection, infection from, infection through, a cause of infection, the onset of infection, resistance to infection, nasty, serious, severe, have, suffer, suffer from, develop, occur, spread, in infection, infection from, infection through, a cause of infection, the onset of infection, resistance to infection	deadly, killer, lethal, be infected with, catch, contract, infect somebody/​something, attack somebody/​something, kill somebody/​something, infection, vaccine, transmission, deadly, killer, lethal, be infected with, catch, contract, infect somebody/​something, attack somebody/​something, kill somebody/​something, infection, vaccine, transmission, computer, email, be infected with, create, develop, attack something, destroy something, spread, threat, warning, protection
Antonyms	health, wellness	antibody, health
Common mistakes	Confused with 'inflection' (change in speech), Using 'infection' to refer to non-medical situations, Incorrectly stating a person is an 'infection' instead of having an 'infection'	Confused with 'bacteria' as they are different types of germs., Using 'viruses' incorrectly in singular contexts., Mispronouncing it as 'virous' rather than 'virus'.
Usage notes	Use 'infection' in medical or health contexts. It's appropriate for conversations with healthcare professionals or when discussing illnesses. Avoid using it in casual or non-serious discussions.	Use 'virus' in medical or technical contexts. Avoid colloquial settings unless joking or referencing technology (e.g., computer virus).

See it in real clips

They attack, like white blood cells fighting an infection.

The Pitt › S1 E1

Good pulse and blood pressure. No signs of infection.

They attack, like white blood cells fighting an infection.

The Pitt › S1 E1

Good pulse and blood pressure. No signs of infection.

Infection

An idea is like a virus. Resilient.

A virus.

An idea is like a virus. Resilient.

A virus.

Virus

Frequently asked questions: Infection vs Virus

What's the difference between Infection and Virus?

Infection: When germs or bacteria get into the body and make you sick. Virus: A tiny living thing that can make you sick.

Which is more advanced: Infection and Virus?

Infection is the highest level, at B2, on the CEFR scale.

Are Infection and Virus the same CEFR level?

Infection: B2, Virus: A2 on the CEFR scale.

What part of speech are Infection and Virus?

Infection: noun, Virus: noun.

Can you show an example of each?

Infection: The doctor confirmed that the patient had a bacterial infection in his lungs. Virus: The doctor explained how a virus can spread from one person to another.

Can I use Infection and Virus interchangeably?

Not always. Infection and Virus are related and overlap in some contexts, but they differ in register, how common they are, and usage, so swapping one for another can change the meaning or tone. Check the differences above before substituting.