Increasing Herd Immunity with Influenza Revaccination

TL;DR

This study uses a contact network model to show that continuous influenza revaccination across seasons can significantly reduce disease spread and protect highly-connected individuals, supporting policies for repeated vaccination.

Contribution

It introduces a two-season contact network model demonstrating the benefits of continuous influenza revaccination on public health outcomes.

Findings

Revaccination reduces influenza attack rates.

Continuity in vaccination protects highly-connected individuals.

Policy implications favor repeated seasonal vaccination.

Abstract

Seasonal influenza is a significant public health concern in the United States and globally. While influenza vaccines are the single most effective intervention to reduce influenza morbidity and mortality, there is considerable debate surrounding the merits and consequences of repeated seasonal vaccination. Here, we describe a two-season influenza epidemic contact network model and use it to demonstrate that increasing the level of continuity in vaccination across seasons reduces the burden on public health. We show that revaccination reduces the influenza attack rate not only because it reduces the overall number of susceptible individuals, but also because it better protects highly-connected individuals, who would otherwise make a disproportionately large contribution to influenza transmission. Our work thus contributes a population-level perspective to debates about the merits of repeated influenza vaccination and advocates for public health policy to incorporate individual vaccine histories.