Wda.delta.RdCompute immune tracking variables as a function of host age and exposure
# S3 method for class 'delta'
Wda(a, FoIpar, tau = 0, hhat = 1, par = par_Wda_delta())age of a host cohort
parameters that define an FoI function
cohort birthday
overrides the value of hbar in par
parameters in a list
a numeric vector of length(a)