The USS George Washington (GW) and the USS Ronald Reagan (RR), 2 US Navy aircraft carriers, experienced almost simultaneous outbreaks of novel H1N1 influenza A in the summer of 2009. We compared the respective epidemic control measures taken and subsequent lessons learned.

Data were collated from both outbreaks to assess various elements including attack rate, isolation/quarantine protocols, and treatment methods. The respective duration of each outbreak was compared with survival curve analysis. The number of personnel affected in each outbreak was compared using χ2 analysis.

Differences were found in the protocols used on the 2 ships. The GW treated about two-thirds of the patients with oseltamivir through day 14 and quarantined all patients meeting case definition throughout the outbreak. Face masks were used throughout. The RR used oseltamivir and quarantined many fewer patients (through days 5 and 3, respectively). No face masks were used after day 5. The outbreaks were similar in duration (GW = 25 days, RR = 27 days, P = .38), but the RR had significantly more cases (n = 253 vs 142, P < .0001). A portion of each group had samples that were confirmed H1N1 by polymerase chain reaction.

GW's protocol, including aggressive oseltamivir treatment of two-thirds of the cases and quarantine throughout the duration decreased the overall number of personnel affected, likely reducing the overall control reproduction number. Both outbreaks were similar in duration. Even though the GW expended significantly more resources than the RR, if the 2009 pandemic H1N1 strain had been as clinically severe as the 1918 pandemic, a more stringent treatment protocol may have been the only way to prevent significant operational impact.(Disaster Med Public Health Preparedness. 2013;7:29-35)

We compared attack rates for novel H1N1 influenza A (H1N1) among various groups aboard an aircraft carrier as influenced by characteristics of their living arrangements.

During an outbreak of H1N1 on board the USS George Washington (GW), group affiliation (department or squadron membership) data were obtained on all patients who were placed in respiratory isolation based on their diagnosis with presumptive H1N1. Because berthing spaces are assigned by department and various characteristics of each department's berthing spaces are known, analysis of attack rates in comparison to these characteristics was possible. Attack rates were compared with the square feet of living space per sailor, occupancy rate of the berthing areas, and size of the berthing areas. These results were further correlated with the mission of the various departments or squadrons.

The average attack rate was 3%, with the highest rates occurring in departments or squadrons whose mission required ongoing contact with civilian populations ashore. The attack rate among officers was 2.04 versus 3.19 among enlisted personnel; this difference was not significant (P = .21). The attack rate for women was 1.90 versus 3.09 for men, which was significant (P = .05). Although attack rates varied considerably based on organizational mission, no correlation was found between attack rate and square feet of living space per person or occupancy rate or size of berthing spaces.

The attack rate of the outbreak overall was limited to 3%. Smaller and more crowded berthing configurations did not contribute to higher attack rates, suggesting that transmission occurs most frequently elsewhere while engaged in other activities such as working, eating, or relaxing. Further studies are necessary to filter out potential correlations or variables not identified in this study, such as the difference between the number of men and women isolated. (Disaster Med Public Health Preparedness. 2012;0:1-5)