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.
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.: Compare effectiveness (def. 3).
- Sometimes ef·fi·cac·i·ty [ef-i-kas-i-tee] /ˌɛf ɪˈkæs ɪ ti/ .
- non·ef·fi·ca·cy, noun
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
How to use efficacy in a sentence
Initial trials should also be evaluated by an International Scientific Advisory Panel—yet to be established—for safety and efficacy before receiving the final go-ahead.A CRISPR Baby Future? New Report Outlines Path to Human Germline Editing | Shelly Fan | September 15, 2020 | Singularity Hub
These trials allow scientists to determine the vaccines’ efficacy and identify side effects that may not have appeared in phase 1 or phase 2 trials.China has quietly vaccinated more than 100,000 people for Covid-19 before completing safety trials | Lili Pike | September 11, 2020 | Vox
We need to assess safety, and we won’t know the efficacy part until much later.AstraZeneca just paused its COVID-19 vaccine trial, and that’s a good thing | Claire Maldarelli | September 9, 2020 | Popular-Science
Meanwhile, other experts have questioned the efficacy of Hong Kong’s mass testing as a preventative measure since people are still free to circulate around the city.Hong Kong’s citywide COVID-19 testing has become a barometer of public trust | eamonbarrett | September 9, 2020 | Fortune
Just last week, FDA commissioner Stephen Hahn cited misleading statistics about the efficacy of using blood plasma to treat severe Covid-19.A third of Americans might refuse a Covid-19 vaccine. How screwed are we? | Brian Resnick | September 4, 2020 | Vox
The eating disorder field remains divided over the potential efficacy of such measures.How Skinny Is Too Skinny? Israel Bans ‘Underweight’ Models | Carrie Arnold | January 8, 2015 | THE DAILY BEAST
On average, the vaccine has an efficacy of about 60 percent.When You Get the Flu This Winter, You Can Blame Anti-Vaxxers | Kent Sepkowitz | January 1, 2015 | THE DAILY BEAST
The efficacy of bandying threats of going to hell met its match in the Civil War.
If there were a pill with such poor efficacy, it might be considered malpractice to prescribe it.‘The Biggest Loser’ Could Be TV’s Most Important Show Ever | Daniela Drake | September 26, 2014 | THE DAILY BEAST
Most Pennsylvanians now support a moratorium on capital punishment until its efficacy can be determined.
The cow happily recovered, which the widow entirely attributed to the efficacy of her pastor's prayer.The Book of Anecdotes and Budget of Fun; | Various
It is, therefore, with pleasure I make known the following recipe, which I am assured has been tried with efficacy.The Book of Anecdotes and Budget of Fun; | Various
Who can understand its nature, its operations, the sufficiency which is not sufficient, and the efficacy which is ineffectual.A Philosophical Dictionary, Volume 1 (of 10) | Franois-Marie Arouet (AKA Voltaire)
The natural reverence for their remains soon passed into a superstitious veneration and belief in their miraculous efficacy.The Catacombs of Rome | William Henry Withrow
As such, the efficacy of prayer in their regard must be judged according to the principles applying to the latter.Mary, Help of Christians | Various
British Dictionary definitions for efficacy
the quality of being successful in producing an intended result; effectiveness
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012