Imperfect vaccine and hysteresis

Area of Science:

• Public Health
• Mathematical Epidemiology
• Behavioral Science

Background:

• Vaccine compliance is crucial for public health, yet achieving high vaccination coverage remains challenging.
• Resurgence of vaccine-preventable diseases highlights the need to understand declining vaccine uptake.
• Imperfect vaccines, offering partial protection, complicate vaccination decisions.

Purpose of the Study:

• To investigate how social imitation dynamics influence vaccination coverage with imperfect vaccines.
• To analyze the impact of vaccine efficacy and perceived costs on vaccination decisions.
• To identify factors contributing to persistent vaccine compliance problems.

Main Methods:

• Mathematical modeling of social imitation dynamics in vaccination.
• Bifurcation analysis to study vaccination equilibria and stability.
• Comparison of spatial versus well-mixed population models.

Main Results:

• Multiple stable vaccination equilibria exist when vaccine efficacy is below a threshold.
• Hysteresis loops observed in vaccination rates concerning cost and effectiveness.
• Hysteresis is more prevalent in spatial populations, acting as a roadblock to uptake recovery.

Conclusions:

• Imperfect vaccine efficacy and social imitation can lead to persistent low vaccination rates.
• Hysteresis phenomena explain the difficulty in recovering vaccination uptake.
• Understanding these dynamics is key to addressing public health challenges in vaccine compliance.