The United States Coast Guard (USCG) Training Center Cape May (TCCM) experienced an outbreak of influenza in July 2023. TCCM is the only recruit training center within the USCG and its training mission is critical to USCG operations. The 2023-24 influenza vaccine was not yet available for distribution and any recruits who might have received vaccination from the preceding year would no longer have adequate protection due to waning effectiveness. Recruits are grouped into companies of 85-110 individuals and arrive weekly to in-process and begin an eight-week rigorous training program before graduating and moving out to join USCG operations across the country. Each company is billeted in its own barrack equipped with rows of bunkbeds with shared bathroom facilities. Recruits eat together as companies in an enclosed dining hall and separation from other companies is challenging due to limited space in the dining facility and time to separate meals among companies of recruits. USCG headquarters (HQ) noted an incidental case of influenza identified in a recruit hospitalized for an unrelated issue on 17 July 23. The TCCM medical clinic director and laboratorian were advised to report any additional cases and to use the 4-plex PCR (SARS-CoV-2/FLUA/FLUB/RSV) testing on any symptomatic individuals with sore throat, congestion, fever, and/or myalgias. On 20 July 23, HQ was notified of 15 total cases at TCCM. Immediate public health measures were implemented to include hand washing, disinfection of surfaces, and social distancing where possible. Implementation of universal oseltamivir prophylaxis (recommended but not required) followed and all identified positive influenza cases were given treatment with oseltamivir. Active case finding through quasi-random sampling of 10 persons from each of four affected companies over five days provided information about the effectiveness of the outbreak measures through identification of symptomatic individuals who would not have presented to the medical clinic for diagnostic testing. Active case-finding provided confidence that mitigation strategies were effective and ensured an accurate understanding of the outbreak. Public health control measures effectively reduced the propagation of cases to zero within two weeks of implementation. Close coordination with the Commanding Officer of TCCM along with incident command meetings of essential partners on the ground and an in-person public health team from HQ staff were critical to ensuring implementation of public health interventions and active case finding. Effective communication among all partners ensured TCCM training operations continued without pause. The response to the TCCM influenza outbreak provides lessons for management of an influenza outbreak in congregate (and, by extension, deployed) settings when personnel are often barracked together and work closely together as teams. Fundamental incident response measures in a congregate/deployed setting can be transformed into a direct public health incident response, critical to ensuring congregate/deployed personnel can effectively continue their operations. Part 2. An assessment of vaccine status and immunity in 26 recruit companies at USCG Training Center Cape May, New Jersey (TCCM) during the period of 14 June 2023 through 24 January 2024 demonstrated an average of 26% of recruits lacking immunity when MMR titers were assessed. The Defense Health Board evaluated MMR booster immunization practices in a report dated May 18, 2020 and determined that universal vaccination to all service members in the wake of mumps outbreaks aboard U.S. Naval vessels and within ground units of the U. S. military were warranted. However, the recommendations were not adopted by the DOD and military services continue the practice of evaluating titers and administering vaccinations according to individual need. Recruit vaccination records are evaluated on the first day of arrival by medical clinic personnel. Any recruit with unknown vaccination status is evaluated with laboratory testing for titers. If titers are not detected, the recruit is administered the vaccine on Day 2. A single dose of MMR results in 93%, 78%, and 97% effectiveness for measles, mumps, and rubella respectively. Two doses are 97% and 88% effective for measles and mumps. A single dose of rubella vaccine confers long-term, probably lifelong, protection. Vaccine induced measles immunity appears to be long- term and probably lifelong in most persons; however, the effectiveness of two doses of MMR against mumps suggest that the effectiveness decreases with time and a third dose of MMR can provide added short term protection for those who are likely to have close contact with a mumps patient. Therefore, a 75% seroprevalence for titers for measles, mumps, and rubella among recruits suggest that a quarter have received zero doses of MMR. Due to high transmissibility of measles, 90% seroprevalence is minimally needed for herd immunity, and 95% population immunity is important to prevent sustained transmission in an outbreak. Measles is not endemic in the US and therefore any case is usually due to importation. However, the consequences of measles occurring at the only recruit training center in the USCG would be significant, with a single case potentially affecting as many as 25 out of 100 recruits in a company, if the case were in the infectious stage. There might be added potential of transmission to recruits in the cohorts from the two preceding weeks since full immunity may not be achieved during that time. Isolation of any recruit with measles would be extremely challenging due to limited capacity at the medical clinic, with minimal potential to isolate within barracks. One can also consider the potential for a mumps outbreak within close living quarters considering waning immunity, and only 88% effectiveness in fully vaccinated individuals. The question is, “Is it time to look again at whether universal vaccination of military recruits is cost and operationally warranted given the findings of undetectable titers in 25% of recruits?”