Outbreak of influenza and rhinovirus co-circulation among unvaccinated recruits, U.S. Coast Guard Training Center Cape May, NJ, 24 July-21 August 2016.

Military and Coast Guard recruits are particularly susceptible to respiratory infections. Although seasonal influenza vaccinations are mandatory for recruits, the vaccine expires annually in June. On 29 July 2016, the U.S. Coast Guard Training Center Cape May, NJ, identified an increase in febrile respiratory illness (FRI) among recruits. During 24 July-21 August, a total of 115 recruits reported symptoms. A total of 74 recruits tested positive for respiratory infections: influenza A (H3) (n=34), rhinovirus (n=28), influenza/rhinovirus co-infection (n=11), and adenovirus/rhinovirus co-infection (n=1), while 41 recruits had no laboratory-confirmed specimen but were considered suspected cases. Only one recruit reported receiving the seasonal influenza vaccine within the previous 12 months. Influenza predominated during 24 July-6 August, whereas rhinovirus predominated during 7 August-20 August. Most (92.2%) cases were identified in four of 10 recruit companies; incidence rates were highest among recruits in weeks 2-4 of an 8-week training cycle. Key factors for outbreak control included rapid detection through routine FRI surveillance, quick decision-making and streamlined response by using a single chain of command, and employing both nonpharmaceutical and pharmaceutical interventions.