Fig. 2

Fixed parameter values of MenW transmissibility and invasiveness before the emergence of MenW:cc11/SA in England and in France. a Age-specific overall prevalence of meningococcal carriage. The estimates and 95% CIs were estimated using weighted linear regression, based on the values reported in Ref. [1]. b Age-specific prevalence of non-MenW:cc11 carriage. c, d Age-specific transmissibility and invasiveness of non-MenW:cc11. We scaled the estimates of overall meningococcal carriage prevalence displayed in A to derive estimates of non-MenW:cc11 (that is, of MenW before the emergence of MenW:cc11/SA), assuming a carriage prevalence of MenW of 2% in 20–24 yo. We then calibrated the transmission risk (c, see Additional file 1) so that the carriage prevalence of non-MenW:cc11 was as displayed in b. Finally, we calibrated the invasion risk of non-MenW:cc11 (d) so that the simulated incidence of MenW was approximately equal to that reported in England or in France before the emergence of MenW:cc11/SA