Table 1.
Intervention strategies and effects on onward transmission.
| Strategy name | Reduction in R0a |
||
|---|---|---|---|
| (Strategy type) | Description | Lowb | Highb |
| Case isolation (mitigation) | Symptomatic cases stay at home for 7 days, reducing non-household contacts during this period. Household contacts remain unchanged. | 15.8% | 18.6% |
| Closing schools and universities + telework (mitigation) | Closing Schools/Universities: Physical closure of all schools and universities (or move to a virtual learning environment). Assumes some increase in contacts in the household and the community during the closure, partially offsetting reductions in transmission at schools and universities. | 15.8% | 16.8% |
| Telework: All government switches to telework to the maximum extent possible, and private businesses are encouraged to telework, resulting in 50% of the working population teleworking. | |||
| Case isolation + household quarantine (mitigation) | Case isolation: same as above | 25.4% | 30.0% |
| Household quarantine: After identifying a symptomatic case in the household, all household members voluntarily remain at home for 14 days. Increased transmission between household members during the quarantine period will partially offset transmission reductions in the community. | |||
| Case isolation + household quarantine + social distancing of >70 s + telework (mitigation) | Case isolation: same as above | 41.9% | 47.7% |
| Household quarantine: same as above | |||
| Social Distancing of >70 s: Reduce contacts among older individuals (>70 years of age) because of their increased risk for severe outcomes and healthcare resource requirements. These individuals reduce contacts outside the home by 50%. | |||
| Telework: same as above | |||
| Lockdown (suppression) | Population-wide social distancing by forced quarantine of all households and workplaces and the border closed to travel. Only essential outings from home are permitted (e.g., food/supplies purchases) and for employees working at businesses deemed essential for continued operation. | 57.7% | 68.2% |
a
R0 = basic reproduction number. It represents the average number of people who will be infected by any given infected person at the early stages of disease spread when there are no control measures.
b
High and Low values of the reduction in transmission associated with each strategy were used to account for uncertainty in societal compliance and strategy effectiveness. These reductions were based on equivalent reductions in Critical Care Bed Occupancy published in Ferguson et al. (2020) (Supplementary Material S2). We added 10 percentage points to reduction values for strategies including telework, based on Willem et al. (2020).