List of top Social And Preventive Medicine Questions on Vaccine efficacy, effectiveness and protective efficacy

An influenza vaccine shows 90% efficacy in a randomized controlled trial but only 85% performance when used in the routine community programme. Which value represents the effectiveness of the vaccine?

An influenza vaccine is evaluated in a well-conducted randomized controlled trial and again during routine community use. The trial value is 90% and the field value is 85%. Which value represents the efficacy of the vaccine?