Halloran M E, Haber M, Longini I M, Struchiner C J
Division of Biostatistics, Emory University School of Public Health, Atlanta, GA 30329.
Am J Epidemiol. 1991 Feb 15;133(4):323-31. doi: 10.1093/oxfordjournals.aje.a115884.
In 1915, Greenwood and Yule noted that for valid vaccine efficacy studies, exposure to infection in the vaccinated and the unvaccinated must be equal (Proc R Soc Med 1915;8(part 2):113-94). The direct effect of a vaccine, however, needs to be defined by the protection it confers given a specific amount of exposure to infection, not just a comparable exposure. In this paper, two classes of parameters are distinguished along lines differing from the conventional distinction between efficacy and effectiveness. Efficacy parameters attempt to control for exposure to infection and represent direct effects on individuals. Direct effectiveness parameters represent a mixture of direct effects on individuals and indirect effects in the population.
1915年，格林伍德和尤尔指出，对于有效的疫苗效力研究，接种疫苗者和未接种疫苗者的感染暴露情况必须相同（《皇家医学会学报》，1915年；8（第2部分）：113 - 94）。然而，疫苗的直接效应需要根据在特定感染暴露量下所提供的保护来定义，而不仅仅是可比的暴露情况。在本文中，两类参数的区分方式与效力和效果之间的传统区分不同。效力参数试图控制感染暴露情况，并代表对个体的直接效应。直接效果参数代表对个体的直接效应和人群中的间接效应的混合。
