Significant differences in immunity to influenza A viruses among communities cannot solely explained by differences in population demographics suggests a study published in Nature Communications this week. This finding suggests that there may be characteristics of communities that drive influenza transmission dynamics apart from individual and household level risk factors.

Variations in influenza incidence between locations are commonly observed on large spatial scales. It is currently unclear whether such variation occurs on small spatial scales and whether it is a result of differences in population demographics or more subtle differences in population structure and connectivity.

Derek Cummings and colleagues selected five communities at random in Guangdong, China and tested blood samples against five recently circulating influenza viruses. They found significant differences in the frequency of detectable immune responses to influenza A viruses among communities that is not explained by the differences in population demographics alone.

This work suggests that the exposure of populations to seasonal influenza differs over much smaller spatial scales than was previously thought. However due to the small sample size further locations will need to be studying in order to determine the specific factors that lead to spatial differences in immunity patterns.