Table 1. Variables in the influenza virus – bacterial co-infection model.

Variables	Definition
X	Number of people susceptible to both influenza virus and bacteria
YFA	Number of people with asymptomatic influenza infection but not colonized with bacteria
YFS	Number of people with symptomatic influenza infections but not colonized with bacteria
ZF	Number of people have recovered from influenza infection
YB	Number of people colonized with bacteria and susceptible to influenza virus
YBFA	Number of co-infected people who are colonized with bacteria first then acquire asymptomatic influenza infection
YBFS	Number of co-infected people who are colonized with bacteria first then acquire symptomatic influenza infection
YFAB	Number of co-infected people who are asymptomatically infected with influenza first and then acquire bacterial colonization
YFSB	Number of co-infected people who are symptomatically infected with influenza first and then acquire bacterial colonization
YP	Number of people who develop secondary bacterial pneumonia
ZFYB	Number of people who have recovered from influenza infection but are still colonized with bacteria.
N	Total number of population