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Factors that make an infectious disease outbreak controllable
Christophe Fraser1, Steven Riley, Roy M Anderson
1Department of Infectious Disease Epidemiology, Imperial College, St. Mary's, London W2 1PG, United Kingdom. c.fraser@imperial.ac.uk
Summary
Public health measures like isolation and contact tracing are effective for controlling infectious disease outbreaks. Their success depends on the timing of infectiousness relative to symptom onset, not just transmissibility.
Area of Science:
- Epidemiology
- Mathematical Biology
- Public Health
Background:
- Emerging infectious agents pose significant public health challenges.
- Controlling outbreaks relies on understanding disease transmission dynamics.
Purpose of the Study:
- To identify properties of emerging infectious agents influencing the success of public health interventions.
- To assess the impact of transmission timing (presymptomatic/asymptomatic) on outbreak control.
Main Methods:
- Utilized a mathematical model to simulate infectious disease spread.
- Estimated key epidemiological parameters (infectiousness, symptom onset, R(0)) from published data.
- Analyzed control measure efficacy based on transmission characteristics.
Main Results:
- The proportion of transmission before symptom onset significantly impacts control success, alongside inherent transmissibility (R(0)).
- Severe acute respiratory syndrome coronavirus and smallpox demonstrated greater controllability with simple measures compared to HIV and pandemic influenza.
- Contact tracing is crucial for estimating presymptomatic and asymptomatic transmission proportions.
Conclusions:
- Simple public health measures (isolation, contact tracing) effectiveness is highly dependent on the timing of infectiousness relative to symptom onset.
- Understanding presymptomatic and asymptomatic spread is critical for managing novel infectious agents.
- Prioritizing estimation of these transmission dynamics during outbreaks is essential for effective control strategies.