Infection-age structured transmission model highlights the efficacy of case-finding operations

Area of Science:

• Epidemiology
• Mathematical Modeling
• Infectious Disease Dynamics

Background:

• Early epidemic control heavily relies on effective case-finding operations.
• Understanding the theoretical efficacy of these operations is crucial for public health preparedness.

Purpose of the Study:

• To develop and analyze an infection-age structured early growth transmission model.
• To assess the theoretical efficacy of various case-finding strategies, including diagnosis, mass screening, and contact tracing.

Main Methods:

• Developed an infection-age structured early growth transmission model.
• Incorporated symptom-based diagnosis, mass screening, and both forward and backward contact tracing.
• Derived integral equations and coupled them with a Lotka-Euler-type equation to form a closed deterministic system for computing early growth rates and reproduction numbers.

Main Results:

• Diagnosis alone demonstrated limited control over early epidemic growth.
• An integrated case-finding scenario, combining diagnosis, mass screening, and contact tracing, substantially suppressed transmission.
• Stronger mass screening and contact tracing are necessary to reduce the effective reproduction number below one when transmission potential is high.

Conclusions:

• The theoretical efficacy of case-finding operations is contingent upon both the intensity of interventions and the underlying transmission structure of the pathogen.
• Integrated case-finding strategies offer a more potent approach to epidemic control compared to isolated diagnostic measures.