Evaluation of safety and efficacy of new vaccines is likely to be especially challenging since the vaccines might not be available until after the pandemic had started.

由于这些新疫苗可能在流感大流行开始之后才能够获得，因而要评估它们的安全性和效力就很可能非常困难。

youdao

The 1960s were when the Food and Drug Administration, in the wake of the thalidomide scandal, started requiring proof of efficacy and long-term safety, and when medicine started relying on clinical trials that compared new treatments to old ones or to inert sugar pills.

FORBES: We Drink More Than Don Draper But We Die Less Often

Almost immediately, the FDA started receiving reports from patients that claimed the 300mg dose was being associated with side effects and reduced efficacy.

FORBES: A Drug Recall That Should Frighten Us All About The FDA