Table 1:

Nonpharmaceutical interventions explored in the model

Intervention typeImpact of interventionModel component
Case detection and isolationCase testing to identify symptomatic cases resulting in isolation of these individuals in their household, thereby reducing community transmission. Agents that are identified via case testing are isolated at home for 14 days. In addition, a proportion of household members also isolate unless they have been previously infected and are immune.Mild symptoms*
Note that by the time agents arrive in the mildly symptomatic state, they have already been infectious for 1 to 3 days, but isolating them in this state will prevent a further 3 to 7 days of potential community transmission. Isolated agents can continue to infect household members, but at a reduced contact rate of 50% as we assume sick individuals will impose some form of physical distancing in the household.
Contact tracing and quarantineContact tracing to identify individuals who have been exposed and infected but are not yet infectious. This intervention is one of the most effective because an agent who is quarantined for 14 days in the exposed state will not be a source of community infection at any point during their infection.Exposed
Physical distancingReduce the number of contacts per day; can be applied to the entire population or targeted by age group. Physical distancing was applied only outside of the household.All agent states
Community closureClosure of schools, workplaces and mixed-age venues either as a proportion (e.g., 100% of schools) or as a threshold (e.g., workplaces with 50 or more assigned agents). Agents who are assigned to a community environment that is closed are forced to stay at home until closure has ended.NA
  • Note: NA = not applicable.

  • * Individuals with severe symptoms are assumed to be too ill to be out in the community; therefore, case testing and isolation applies only to agents with mild symptoms.