Risk-Based Ring Vaccination: A Strategy for Pandemic Control and Vaccine Allocation

Dinh Song An Nguyen, Marie-Laure Charpignon, Kathryn L Schaber, Maimuna S. Majumder, Andrew Perrault

Keywords: agent-based modeling, ring vaccination, Ebola, public health

TL;DR: We designed an effective risk-based ring vaccination strategy that is able to contain an outbreak under resource constraints.

Abstract: Throughout an infectious disease crisis, resources that can be used to slow and prevent spread are often scarce or expensive. Designing control policies to optimally allocate these resources to maximize objectives is challenging. Here, we study the case of ring vaccination, a strategy that is used to control the spread of infection by vaccinating the contacts of identified infected individuals and their contacts of contacts. Using agent-based modeling to simulate an Ebola outbreak, we introduce a risk-based ring vaccination strategy in which individuals in a ring are prioritized based on their relative infection risks. Assuming the risk of transmission by contact type is known and a fixed supply of vaccine doses is available on each day, we compared this strategy to ring vaccination without prioritization and randomized vaccination. We find that risk-based ring vaccination offers a substantial advantage over standard ring vaccination when the number of doses are limited, including reducing the daily infected count and death count, and shifting the pandemic peak by a considerable amount of time. We believe that control policies based on estimated risk can often offer significant benefits without increasing the burden of administering the policy by an unacceptable amount.