BACKGROUND: Influenza prevention is recognized as a high priority in the military, as respiratory illness can devastate military readiness and is one of the most common causes of lost duty time among young adults in the military. The Department of Defense (DoD) Global, Laboratory-Based, Influenza Surveillance Program is a year-round, sentinel-based program located at the U.S. Air Force School of Aerospace Medicine, Wright-Patterson AFB, Ohio. Various activities, including calculating vaccine effectiveness (VE), are conducted in support of the program’s primary goals: prevent influenza infections, reduce morbidity and mortality, and ensure force health protection.
METHODS: Nasal wash specimens were collected from DoD beneficiaries presenting for treatment and meeting the influenza-like illness case definition of fever ≥100.5°F and cough or sore throat, with symptom onset within 72 hours. Specimens received from DoD medical treatment facilities in the United States were tested using viral culture, quantitative reverse transcriptase polymerase chain reaction, and FilmArray®. VE estimates were calculated using a case-control method. Odds ratios were determined by logistic regression and were adjusted for age, region, and collection period (collapsed into four equal quartiles). These estimates used data only from service member dependents.
RESULTS: The program received 6,291 specimens from 89 locations during the 2014-2015 season. Of these, 1,798 were positive for influenza A: 1,794 A(H3N2) and four A(H1N1)pdm09. Two hundred fifty-seven specimens were positive for influenza B: 83 B/Yamagata, 34 B/Victoria, and 140 influenza B, unknown lineage. Two dual influenza co-infections were identified. The sample size for the dependents’ analysis was 2,403 (869 cases and 1,534 controls). Data were analyzed by beneficiary group and vaccine type. Overall, VE estimates conferred a low level of protection at 27% [12.8, 39.6].
CONCLUSIONS: The DoD Global, Laboratory-Based, Influenza Surveillance Program has more than 90 sentinel sites and the ability to identify and sequence influenza strains from areas of the world that lack coverage by the World Health Organization or the Centers for Disease Control and Prevention. This program has access to electronic vaccination data, allowing us to perform mid-season VE estimates. Due to these unique capabilities, our data and analyses help inform the Food and Drug Administration’s influenza vaccine selection annually.