[vannevar]

I believe this model accounts for such individual response:

"Heterogeneity in contact structure and individual variation in infectivity, susceptibility, and resistance are key factors..." (emphasis added)

[AstralStorm]

In general, that's one of those anomalous diffusion problems. Unfortunately, there are too many parameters to estimate without simplifying the model. So the reasonable solution is to take a maximum expected value of each and you can still be wrong.

Important data we do not know is chiefly how effective SARS aerosols are and at what range and time.