Table 1. Summary of risk assessment scientific criteria.

Risk Elements for Likelihood Risk Score	Representative Criteria (examples)
Receptor binding properties	• α2,3-linked sialic acids • α2,3 and α2,6-linked sialic acids • α2,6-linked sialic acids
Transmission in animal models	• No direct or respiratory droplet • Consistent direct contact • Consistent respiratory droplet
Genomic characteristics	• No molecular signatures of human infection and disease. • Molecular signatures • Contains genes derived from a virus circulating in mammals
Infection in animals	• Wild species • Poultry or mammals • Endemicity • Numbers of impacted animals
Geographic distribution in animals	• Local and contained • Regional within well-defined geographic boundaries. • Widespread no boundaries
Risk Elements for Impact Risk Score
Disease severity (human)	• Uncomplicated • Uncomplicated but some severe illness (underlying conditions) • Severe disease
Population immunity	• Cross-reactive antibodies > 30% of population except children < 17 • Cross-reactive antibodies > 30% of people >50 • Minimal (<10%) cross-reactive antibodies
Susceptibility to antiviral treatment	• Resistant to adamantanes • Above + resistant to 1 NA inhibitor • Above + resistant to > 1 NA inhibitor
Genomic characteristics	As above
Receptor binding properties	As above
Human infection	• Single case • Isolated or sporadic cases • Frequent separate clusters