Immunization coverage required to prevent outbreaks of dog rabies

Area of Science:

• Veterinary Epidemiology
• Infectious Disease Dynamics
• Public Health

Background:

• The World Health Organization (WHO) recommends 70% dog vaccination coverage to control rabies.
• This recommendation is based on empirical observations of vaccination coverage and rabies incidence.
• Previous estimates of critical vaccination coverage (pc) lack a strong theoretical foundation.

Purpose of the Study:

• To estimate the critical vaccination coverage (pc) for rabies elimination in dog populations using epidemic theory.
• To compare theoretical estimates of pc with the current WHO recommendation.
• To assess the effectiveness of the 70% vaccination coverage target.

Main Methods:

• Utilized epidemic theory and data from four distinct rabies outbreaks (USA, Mexico, Malaysia, Indonesia).
• Estimated the basic case reproduction number (R0) from the initial rate of case increase during epidemics.
• Calculated the critical vaccination coverage (pc) based on R0 estimates.

Main Results:

• Estimated R0 values ranged from 1.62 to 2.33.
• Derived critical vaccination coverage (pc) estimates between 39% and 57%.
• The 70% WHO recommendation provides a high probability (≥96.5%) of preventing major rabies outbreaks.

Conclusions:

• Epidemic theory provides a robust method for estimating critical vaccination coverage for rabies control.
• The current WHO recommendation of 70% dog vaccination coverage is a conservative yet effective target for preventing major rabies epidemics.
• Understanding R0 is crucial for setting appropriate vaccination coverage goals in animal rabies control programs.