Table 1.

List of parameters and other notation

Symbol	Definition	Values
X	Health status	0 - frail
		1 - healthy
V	Vaccination status	0 - unvaccinated
		1 - vaccinated
Y	ARI and influenza infection status	0 - no ARI
		1 - NFARI
		2 - FARI
M	Seeking medical care for ARI	0 - no
		1 - yes
T	Result of test for influenza infection	0 - negative
		1 - positive
C A	Case/control status in TND study	0 - control
		1 - case
C B	Case/control status in TCC study	0 - control
		1 - case
B	Participating in TCC study	0 - no
		1 - yes
π	Probability of having better health status (i.e. healthy persons)	0.7
α x	Probability of being vaccinated for a person of health status x
β vx	Probability of NFARI for a person of vaccination status v and health status x
${\rho }_{\beta }=\frac{{\beta }_{1x}}{{\beta }_{0x}}$	Ratio comparing vaccinees and non-vaccinees w.r.t. probability of NFARI	0.5-2.0
${\eta }_{\beta }=\frac{{\beta }_{v1}}{{\beta }_{\mathit{\text{vo}}}}$	Ratio comparing healthy and frail persons w.r.t. probability of NFARI	0.5-1.0
γ vx	Probability of FARI for a person of vaccination status v and health status x
${\rho }_{\gamma }=\frac{{\gamma }_{1x}}{{\gamma }_{0x}}$	Ratio comparing vaccinees and non-vaccinees w.r.t. probability of FARI	0.4a
${\eta }_{\gamma }=\frac{{\gamma }_{v1}}{{\gamma }_{v0}}$	Ratio comparing healthy and frail persons w.r.t. probability of FARI	0.5-1.0
δ SN	Probability of seeking medical care for ARI for an unvaccinated frail person with NFARI
δ SF	Probability of seeking medical care for ARI for an unvaccinated frail person with FARI
λ	multiplier for the probability of seeking medical care for FARI or NFARI for a healthy person	0.5-2.0
Ψ F	multiplier for the probability of seeking medical care for FARI for a vaccinated person	0.5-1.0
τ e	Probability that a person of illness/infection status e tests positive for influenza infection	τ 1=0, τ 2=1

^aAssumes a true VE of 60%. Thus, the probability of FARI in a vaccinee is 40% that of a non-vaccinee