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Volume 13, Number 9—September 2007

Frequent Travelers and Rate of Spread of Epidemics

T. Déirdre Hollingsworth*Comments to Author , Neil M. Ferguson*, and Roy M. Anderson*
Author affiliations: *Imperial College London, London, United Kingdom;

Main Article

Table 1

Parameter descriptions and values of epidemiologic model that simulates exportation of cases from SARS-like and influenza-like epidemics*

Description Parameter Value (reference)
SARS Influenza
Basic reproductive number R0 2.5 (13) 1.8 (14)
Latent period, d TL 4 (13) 1.5 (14)
Infectious period, d TI 10 (13) 1.1 (14)
Generation time, d Tg = TL + TI 14 2.6
Epidemic doubling time, d td = Tg / (R0 – 1) ln2 6.5 2.3
International travel
Proportion of population who are high-frequency fliers r 0–0.5
Mixing between groups: φ = 1, random mixing; φ = 0, 
 assortative mixing φ 0–1
Relative probability of flying of high-frequency fliers f 20
Mean probability of flying per day ε 0.005 (9)
Probability of flying per day of high-frequency fliers εH = f / 1 + (f – 1)r ε 0.084
Probability of flying per day of low-frequency fliers εL = 1 / 1 + (f – 1)r ε 0.042
Probability of a case being exported
Homogeneous flying patterns L = TLε 0.02 0.008
High-frequency fliers lH = TLεH 0.34 0.13
Low-frequency fliers lL = TLεL 0.017 0.006

*SARS, severe acute respiratory syndrome.

Main Article

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