Table 1.

Outbreak control measures in Singapore. Observed case data were used to estimate the effectiveness of each measure. Cases are defined as infected individuals that tested positive and are notified, while infections include all notified and missed infected individuals

Control measure (Aims)	Description	Observed data (●) and modelled outputs (◆)
Border control (Minimise disease introduction into community)	■ Limiting the number of incoming travellers from countries with ongoing outbreaks ■ Quarantine or restricting movement of incoming travellers	◆ Number of missed imported infections
Case finding (Targeted testing at known or potential source(s) of infection)	■ Testing of symptomatic travellers upon arrival or when they developed symptoms during quarantine ■ Testing regime for non-symptomatic travellers	● Imported case data
	■ Testing of suspect cases (e.g. persons with clinical signs and symptoms suggestive of pneumonia or severe respiratory infection, persons with acute respiratory infection and travel history to regions with ongoing outbreak) ■ Routine testing of high-risk populations (e.g. healthcare workers, nursing home residents) ■ Ad-hoc testing during cluster outbreak investigations	● Local unlinked case data ◆ Effectiveness of case finding
Contact tracing (Targeted testing at potential routes of infection)	■ Interviewing COVID-19 cases or use of Bluetooth contact tracing devices to identify close contacts ■ Testing of symptomatic contacts ■ Testing of contacts before the end of their quarantine	● Local linked case data ◆ Effectiveness of contact tracing
Use of other non-pharmaceutical interventions and vaccines (Untargeted community- or population-level preventive measures)	■ Physical distancing ■ School and venue closure ■ Large-scale population movement restrictions and the corresponding need to work-from-home ■ Population-wide face mask usage ■ Pre-event testing/vaccination ■ Accelerated development and roll-out of COVID-19 vaccines (primary doses and boosters) with priority given to frontline workers and the elderly before progressively offered to younger age groups	◆ Average number of secondary cases generated by a single infectious individual over the course of the entire infectious period (i.e. R)