Sampling considerations for detecting genetic diversity of influenza viruses in the DoD Global Respiratory Pathogen Surveillance Program.

The Department of Defense (DoD) Global Respiratory Pathogen Surveillance Program annually monitors the genetic diversity of influenza viruses circulating in DoD beneficiary populations. This program relies on a global network of partners across the DoD to submit respiratory specimens throughout the influenza season. In previous seasons, representative specimens for sequencing were chosen because of cost and time restrictions associated with reliance on Sanger-based sequencing technology. The effect of this specimen prioritization for sequencing has not been previously examined in the respiratory surveillance program. Here, specimen prioritization was simulated by iteratively subsetting sequencing data sets from 1 October 2013 through 15 March 2017 to determine how prioritizing affects common metrics of genetic diversity. Prioritization of specimens did not meaningfully affect calculations of average influenza genetic diversity within seasons or subtypes. Because of the high genetic diversity of influenza, prioritizing resulted in fewer unique viruses and less accurate measures of geographic relationships although it still provided relevant estimates. Given the advent of cost-effective next-generation sequencing approaches, all programs should carefully consider how best to prioritize influenza sequencing to recover meaningful information on the evolutionary dynamics of the virus.