Is the basic reproductive number (R0) for measles viruses observed in recent outbreaks lower than in the pre-vaccination era?

摘要

The basic reproductive number R, is the average num- ber of individuals directly infected by one infectious case (secondary cases) during the entire infectious period, when the infectious agent has entered a totally susceptible population [3]. The effective basic repro- ductive number R, on the other hand, is the reproduc- tive number observed when of a part of the population is immunised (I) [3]. In this situation, the reproductive number decreases from R, to R=R,—R,I [3]. Outbreaks can be interrupted when R=1.