In the planner's view, Rumsfeld had two goals: to demonstrate the efficacy of precision bombing and to "do the war on the cheap."—Seymour M. Hersh, New Yorker, 7 Apr. 2003Vaccines exist, but their efficacy against aerosolized plague is unknown.—Sharon Begley et al., Newsweek, 8 Oct. 2001… efficacy does not have to be demonstrated before homeopathic products are marketed.—Alison Abbott et al., Nature, 26 Sept. 1996
questioned the efficacy of the alarms in actually preventing auto theft
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Kennedy is a longtime anti-vaccine advocate who is now using his position as the top US health official to spread misinformation and doubt about the safety and efficacy of vaccines.—Beth Mole, ArsTechnica, 2 Apr. 2025 Kennedy, an environmental lawyer, has a history of sowing doubts about the safety and efficacy of vaccines.—Manas Mishra, USA Today, 31 Mar. 2025 Fewer employees mean less manpower to evaluate the safety and efficacy of new drugs that could dramatically impact diseases like cancer, diabetes and heart failure—issues that affect millions of Americans.—Omer Awan, Forbes.com, 30 Mar. 2025 Marks is credited with coining the name and concept for Operation Warp Speed, the effort during President Trump’s first term to rapidly manufacture vaccines while they were still being tested for safety and efficacy.—Michael Casey and Matthew Perrone, Los Angeles Times, 29 Mar. 2025 See All Example Sentences for efficacy
Word History
Etymology
borrowed from Latin efficācia, from efficāc-, efficāx "capable of fulfilling a function, efficacious" + -ia-y entry 2
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