# calc_risk_mult: Calculate risk from mulitple pathogen exposures In bryanmayer/multdr: Simulating and fitting multiple exposure infectious disease dose-response models

## Description

This function takes mulitple pathogen exposure and calculates the risk of infection over their persistence within host

## Usage

 ```1 2``` ```calc_risk_mult(exposure_series, exposure_times, survival_time = Inf, hazard_risk, clr, na.zero = F, log.surv = F) ```

## Arguments

 `exposure_series` The values of repeated pathogen exposures `exposure_times` The times of exposures `survival_time` the final time to calculate survival to (default infinity) `hazard_risk` The per time risk of exposure during persistence `clr` The clearance rate of exposure

## Details

The risk for a single exposure is derived in `calc_risk`. The accumulation of exposure assuming exponential clearance is independent.

S(t) = exp(-β/c *sum(i = 1..n) p_i *(1 - exp(-c(T - t_i))

which simplifies as T -> Inf to

S(T) = exp(-β/c *sum(i = 1..n) p_i)

## Value

risk calculation over the time specified in survival time

`calc_risk for single exposures.`
 ```1 2 3 4 5 6 7 8``` ```##Single exposure examples calc_risk_mult(1e8, 0, 1, 1e-8, 1) # should return same as calc_risk(1e8, 1, 1e-8, 1) calc_risk_mult(1e8, 1, 2, 1e-8, 1) # should return same as calc_risk(1e8, 1, 1e-8, 1) ## multiple exposures exposures = c(1e7, 1e9, 1e5); exp_times = c(0, 1, 2) calc_risk_mult(exposures, exp_times, 3, hazard_risk = 1e-9, clr = 1) calc_risk_mult(exposures, exp_times, hazard_risk = 1e-9, clr = 1) #total risk 1-exp(-1e-9/1 * sum(exposures)) ```