Hicks N R
J R Coll Gen Pract. 1989 Apr;39(321):151-2.
Doubts were expressed about the effectiveness of measles vaccination during a measles outbreak in a Bristol primary school. Investigation of this outbreak showed that the vaccine uptake rate was 89%, vaccine effectiveness was 84% and that 57% of children developing measles had a history of previous measles vaccination. This apparent paradox arises because, for any vaccine that is not 100% effective, as the vaccine uptake rate rises so the percentage of cases previously vaccinated also rises. An understanding of this relationship may avoid unjustified loss of confidence in vaccine effectiveness as vaccine uptake increases.
在布里斯托尔一所小学的麻疹疫情期间，有人对麻疹疫苗接种的有效性表示怀疑。对此次疫情的调查显示，疫苗接种率为89%，疫苗有效性为84%，且患麻疹的儿童中有57%曾接种过麻疹疫苗。出现这种明显矛盾的原因是，对于任何并非100%有效的疫苗，随着疫苗接种率上升，之前接种过疫苗的病例百分比也会上升。理解这种关系可以避免随着疫苗接种率提高而对疫苗有效性产生无端的信心丧失。
