Before revision:  In this setting, the virus' basic reproductive number R _0, which characterizes the average number of secondary cases generated by each primary case, takes on a significant importance in the quantification of the potential scope of the pandemic .
After revision:  In this setting, the virus' basic reproductive number R _0, which characterizes the average number of secondary cases generated by each typical primary case -- is central in the quantification of the potential scope of the pandemic .