noun · academic

efficacy

UK/ˈefɪkəsi/US/ˈɛfɪkəsi/EF·fi·ca·cy

Band 7+task2task1speaking

the ability of an intervention to produce the desired effect under controlled conditions

Examples

Phase III trials are the main way to measure a vaccine's efficacy.

High efficacy in trials does not guarantee the same effect in the real world.

The drug showed good efficacy against the targeted disease.

Band 8 sentence

Although the vaccine demonstrated high efficacy in randomized trials, post-marketing surveillance assessed its effectiveness across populations.

Collocations

  • efficacy of the vaccine
  • demonstrate efficacy
  • high efficacy

Word family

effective adjectiveeffectiveness noun

Common mistakes

efficiency of the drugefficacy of the drug

effectiveness in trialefficacy in trial

Say it for a higher band

5effect6effectiveness7+efficacy

Synonyms

effectiveness

Easily confused

effectiveness

A vaccine can have high efficacy in clinical trials but lower effectiveness in the general population.

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