Symbols  Definition  Virulence Increased  Virulence Decreased
𝜇I  Infected death rate (natural death rate + disease induced death rate)  ↑  ↓
𝜂 = (⍵ − ε−1)  SARS-CoV-2 incubation period  ↓  ↑
1/⍵  Expected time in the asymptomatic state  ↑  ↓
ν  Recovery rate (average of 3 to 6 weeks)  ↓  ↑
p  Percent that moves along the “mild” recovery track  ↓  ↑
βA  Contact rate of people with people × transmission probability of people to people by A-person  ↑  ↓
βI  Contact rate of people with people × transmission probability of people to people by I-person  ↑  ↓
𝜎A  Contact rate of person with environment) × (probability of shedding by A-people to environment  ↑  ↓
𝜎I  Contact rate of person with environment × probability of shedding by I-people to environment  ↑  ↓
1/ε  Average number of days before infectious  ↓  ↑