efficacy

American  

[ef-i-kuh-see] / ˈɛf ɪ kə si /

Sometimes efficacity

noun

plural

efficacies

1. the capacity for producing a desired result or effect.

   Short, frequent periods of practice were shown to have greater efficacy than longer and less frequent ones.

2. a measure of the success of a vaccine or other pharmaceutical when used in the controlled environment of a clinical trial, as opposed to in the real world.

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efficacy British  

/ ˈɛfɪkəsɪ /

noun

1. the quality of being successful in producing an intended result; effectiveness

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Other Word Forms

• nonefficacy noun

Etymology

Origin of efficacy

First recorded in 1520–30; from Latin efficācia, from efficāc- (stem of efficāx ) “effective, effectual” + -ia, noun suffix; efficacious ( def. ), -y ³ ( def. )

Example Sentences

The FDA said Moderna failed to adequately compare the vaccine to its peers, though it didn’t cite safety or efficacy issues in a letter to the company.

From The Wall Street Journal

Moderna says federal regulations don’t require that type of comparison to establish efficacy.

From Barron's

The letter did not identify any safety or efficacy concerns regarding the mRNA vaccine, said Moderna, which added the shot was accepted for review in the European Union, Canada and Australia.

From Barron's

“It’s a peptide. It’s a large protein inside the pill that gives you that incredible efficacy.”

From MarketWatch

“It’s a peptide. It’s a large protein inside the pill that gives you that incredible efficacy.”

From MarketWatch

Related Words

• adequacy
• competence
• effectiveness
• potency
• virtue