Transmission of severe acute respiratory syndrome in dynamical small-world networks

TL;DR

This paper models SARS transmission using small-world networks, emphasizing the role of superspreaders and hospital settings, and suggests strategies like outpatient treatment to prevent mass outbreaks.

Contribution

It introduces a network model for SARS that highlights the importance of biological contagiousness and social network structure over contact heterogeneity.

Findings

Superspreaders are biologically contagious patients.

SARS spreads mainly in hospitals and small-world networks.

Treating suspected cases without hospitalization can reduce transmission.

Abstract

The outbreak of severe acute respiratory syndrome (SARS) is still threatening the world because of a possible resurgence. In the current situation that effective medical treatments such as antiviral drugs are not discovered yet, dynamical features of the epidemics should be clarified for establishing strategies for tracing, quarantine, isolation, and regulating social behavior of the public at appropriate costs. Here we propose a network model for SARS epidemics and discuss why superspreaders emerged and why SARS spread especially in hospitals, which were key factors of the recent outbreak. We suggest that superspreaders are biologically contagious patients, and they may amplify the spreads by going to potentially contagious places such as hospitals. To avoid mass transmission in hospitals, it may be a good measure to treat suspected cases without hospitalizing them. Finally, we indicate that SARS probably propagates in small-world networks associated with human contacts and that the biological nature of individuals and social group properties are factors more important than the heterogeneous rates of social contacts among individuals. This is in marked contrast with epidemics of sexually transmitted diseases or computer viruses to which scale-free network models often apply.