Respiratory pathogen surveillance trends and influenza vaccine effectiveness estimates for the 2018-2019 season among Department of Defense beneficiaries.

This report primarily focuses on the data collected and analyzed from the worldwide network of sentinel military treatment facilities chosen to participate in the Department of Defense Global Respiratory Pathogen Surveillance (DoDGRS) program. Sites that participated in the 2018-2019 DoDGRS program submitted 24,320 respiratory specimens for diagnostic testing. Clinical results showed a total of 5,968 positive influenza cases. In the beginning of the season, starting in surveillance week 48, influenza A(H1N1)pdm09 was the predominant subtype. The predominant subtype switched to influenza A(H3N2) beginning in week 6 and continued through the end of the season. Influenza B virus detection was less common during the surveillance period (i.e., 1% of total submitted specimens and 5% of total influenza detected). In addition to routine surveillance, the DoDGRS program also conducts vaccine effectiveness (VE) studies twice per year to determine interim and end of season estimates. Overall, the adjusted end of season VE for all dependents regardless of influenza type was 30% (95% CI: 22%-38%).