Word of the Week: Multivalent

Each week, Verywell explains a term from health, medicine, science, or technology.

Multivalent

How to say it: Multivalent (muhl-tee-VAY-luhnt)

What it means: Having more than one of something included in it (for example, antibodies or chromosomes).

Where it comes from: Latin, valentia, “strength”

Where you might see or hear it: In medicine, the word part “-valent” is often applied to vaccines. For example, a vaccine might be monovalent, bivalent, quadrivalent, or multivalent. The term gives you a sense of how the vaccine was made and how much protection it could offer.

Vaccines “train” your body to mount a response to a germ, like a virus. However, there are many germs that can make you sick and germs can change over time.

One vaccine may not protect against them all, but vaccine makers try to cover as many germs and their changes (variants) as they can.

The COVID-19 vaccines are a good example. The first vaccines that were available only protected against the first virus that caused COVID—what’s called a monovalent vaccine. Now, there are more strains of the virus than just the original one.

If you’ve been talking with your provider about getting a COVID booster shot, they might explain to you that Pfizer and Moderna are working on bivalent versions of their mRNA shots. These new forms of the vaccine will try to train the body to respond to more than one variant of the COVID virus.

The hope is that the updated COVID vaccines will continue to offer protection as the virus evolves.

When you might want to use it: If you’re talking to your loved ones about getting an annual flu shot, they might wonder why flu vaccines are called quadrivalent.

You could explain to them that the term means the vaccine was made to protect against four strains of the flu virus (quad means four).

If your loved one needs a pneumonia vaccine, you might be surprised to learn that these shots can be 23-valent!