Chapter 8SIR Models

So=9998 Io=2 Ro=0 duration of Infection= 2 days

Recoveries=(Infected Population)/(duration of infection)

Can use summer for Affected population

Infectivity (rate)=0.25 per contactContacts per day=6 per infected personTotal contact per day=6 * Infected Population

Recoveries per day =Infected population / infection duration

Sensitivity Analysis

• Contact number = (infectivity) (contacts per day) (infection duration)

Sometimes referred to at Ro the reproductivity number(The number of new infections) / (a single infected person)

R>1 epedemic R<1 disease dies out

Sensitivity run Infectivity=1-50% 2-25% 3-12.5%

Sensitivity run Infection duration = 1-4 days 2-2 days 3-1 day

Policy analysis

• What can we do??

1918 influenza pandemic

50 to 100 million died worldwide

1918 Influenza: the Mother of All PandemicsJeffery K. Taubenberger* and David M. MorensEmerging Infectious Diseases •

www.cdc.gov/eid Vol. 12, No. 1, January 2006