Arrival Model

The arrival testing regime of a strategy is comprised of two rounds of testing: pre-departure and arrival testing. Pre-departure testing is done before an individual returns to the central location. If they test positive, they stay at their current location and are responsible for their own isolation. Upon receiving a negative pre-departure test, the individual travels to the central location where they take an arrival test. If they are positive, isolation must be provided for them.

Given an arrival testing regime, the percent of the population that were discovered in pre-departure testing and the percent of the population that were discovered in arrival testing can be computed based on test sensitivities and compliance. These discoverd people may be infected or recovered people that were hidden.

The simulation is initialized with both those discovered in pre-departure testing and arrival testing as discovered and recovered. The recovered population that was hidden and the infected population not discovered through the arrival process stays hidden in recovered and infected respectively.

In reporting metrics when an arrival period is being considered, the results of the simulation are tapered for the duration of the arrival period. This tapering assumes the the population returns at a constant rate through the arrival period. The simulation results are independent of the arrival period as the simulation code only supports a constant population. Hence, metrics are pessimistic in the sense that the simulation begins with the full level of internal interaction amongst the population even though the population hasn’t fully arrived. The effects of this can be counteracted by supplying transmission multipliers to the simpar.strategy.Strategy class.