Mapping the spread of seasonal influenza
viruses

Nature

Evolution
Embargo




London: Monday 08 June 2015 16:00 (BST)
New York: Monday 08 June 2015 11:00 (EDT)
Tokyo: Tuesday 09 June 2015 00:00 (JST)
Sydney: Tuesday 09 June 2015 01:00 (AEST)
Not all seasonal influenza viruses circulate around the world in the same way, a study
published in Nature this week demonstrates. Compared with A/H3N2, the most frequent and
severe influenza subtype, A/H1N1 and B viruses do not show the same degree of global
movement but persist for longer periods of time locally. Understanding the dynamics of
influenza viruses is an important scientific and public health challenge; the latest research
provides new insights on the circulation patterns of A/H1N1 and B viruses, which have not
been studied in as much detail as the more common A/H3N2 viruses.
An analysis of nearly 10,000 seasonal human influenza virus sequences over a 12-year
period, performed by Colin Russell, Trevor Bedford, and colleagues, reveals that A/H3N2
viruses move between regions more frequently than A/H1N1 and B viruses. One reason for
this variation may be the rates at which these viruses evolve, the authors suggest. A/H3N2
viruses evolve relatively quickly and routinely infect people of all ages, but A/H1N1 and B
viruses evolve more slowly and mainly infect children. As children travel long distances
much less than adults this factor may account for differences in the global circulation of
viruses. The slower rates of evolution of A/H1N1 and B viruses compared with A/H3N2
viruses may also explain why A/H1N1 and B viruses cause fewer major epidemics than
A/H3N2 viruses.
Article and author details

Global circulation patterns of seasonal influenza viruses vary with
antigenic drift
Corresponding Author
Colin Russell, Cambridge
University of Cambridge, Cambridge, United Kingdom
Email: car44@cam.ac.uk, Tel: +44 1223 761358
DOI
10.1038/nature14460
Online paper*
http://nature.com/articles/doi:10.1038/nature14460
* Please link to the article in online versions of your report (the URL will go live after the embargo
ends).