Table 2.

Epidemiological parameters.

parameter		values per year unit	remarks/sources
r	births per year	0.0127	r = d2(d1 + f)/(d2 + f)
f	maturity rate	1/19
d1	juvenile death rate	20/100 000	US Census, CDC/NCHS
d2	adult death rate	1/55
ks,1	juvenile death rate from varicella (no vaccine)	1/100 000	[3]
ks,2	adult death rate from varicella (no vaccine)	20/100 000
kv,1	varicella mortality of vaccinated juveniles	1/10 000 000	[1]
kv,2	varicella mortality of vaccinated adults	20/10 000 000
σ	1/duration of incubation period	26	[16]
δs	1/duration of infectious period (no vaccine)	52
δv	1/duration of infectious period if vaccinated	81	[17]
β1	transmission rate—juveniles to juveniles	1760	based on Ro = 9.4 and the probability (approx. 90%) of acquiring varicella by age 20 prior to the availability of vaccine
β2	transmission rate—adults to adults, adults to juveniles and juveniles to adults	250
v	vaccination probability	(variable of interest)