Predictive Modeling of Influenza Shows the Promise of Applied Evolutionary Biology

Abstract

Seasonal influenza is controlled through vaccination campaigns. Evolution of influenza virus antigens means that vaccines must be updated to match novel strains, and vaccine effectiveness depends on the ability of scientists to predict nearly a year in advance which influenza variants will dominate in upcoming seasons. In this review, we highlight a promising new surveillance tool: predictive models. Based on data-sharing and close collaboration between the World Health Organization and academic scientists, these models use surveillance data to make quantitative predictions regarding influenza evolution. Predictive models demonstrate the potential of applied evolutionary biology to improve public health and disease control. We review the state of influenza predictive modeling and discuss next steps and recommendations to ensure that these models deliver upon their considerable biomedical promise.

Keywords: Influenza; Predictive evolution; predictive modeling; vaccine strain selection.

Figure 1

Schematic of the influenza surveillance and vaccine strain selection process

Figure 2

Accumulation of Newly Sampled Complete HA Gene Sequences in GISAID EpiFlu™ over the Course of a March–March Year. Top: Cumulative count of sequences deposited in EpiFlu™ as a function of time to submission (difference between sampling date and submission date). Sequences are grouped by collection year. Bottom: Accumulation of sequence data for the year 2016 by geographic region. Plotted data was obtained by downloading sequence records from EpiFlu™ database (data downloaded on 31st March 2017), selecting only sequences that were submitted to and published directly in GISAID, and comparing collection date and submission date metadata. Abbreviation: HA, hemagglutinin.

Figure 3

Approximate calendar of the vaccine update process for the quadrivalent vaccine. Vaccine strains are determined at meetings in February (for the Northern Hemisphere) and September (for the Southern Hemisphere), so that vaccine production and delivery can be completed prior to the onset of each hemisphere’s influenza season. Influenza surveillance, and vaccine development and production are underway year-round.

Figure 4

The multi-scale process of influenza evolution, with patterns and possible sources of predictability at each scale.