Neutralizing and Neuraminidase Antibodies Correlate With Protection Against Influenza During a Late Season A/H3N2 Outbreak Among Unvaccinated Military Recruits.

BACKGROUND: Antibodies that inhibit hemagglutination have long been considered a correlate of protection against influenza, but these antibodies are only a subset of potentially protective antibodies. Neutralizing and neuraminidase antibodies may also contribute to protection, but data on their associations with protection are limited. METHODS: We measured preoutbreak hemagglutinin pseudovirus neutralization (PVN) and neuraminidase inhibition (NAI) antibody titers in unvaccinated military recruits who experienced an H3N2 influenza outbreak during training. We conducted a case-control study to investigate the association between titers and protection against influenza illness or H3N2-associated pneumonia using logistic regression. RESULTS: With every 2-fold increase in PVN titer, the odds of medically attended polymerase chain reaction-confirmed H3N2 infection (H3N2+) decreased by 41% (odds ratio [OR], 0.59; 95% confidence interval [CI], .45 to .77; P < .001). Among those who were H3N2+, the odds for pneumonia decreased by 52% (OR, 0.48; CI, .25 to .91; P = .0249). With every 2-fold increase in NAI titer, the odds of medically attended H3N2 infection decreased by 32% (OR, 0.68; 95% CI, .53 to .87; P = .0028), but there was no association between NAI titers and H3N2-associated pneumonia. There was also no synergistic effect of PVN and NAI antibodies. CONCLUSIONS: PVN and NAI titers were independently associated with reduced risk of influenza illness. NAI titers associated with protection had greater breadth of reactivity to drifted strains than PVN titers. These findings show that PVN and NAI titers are valuable biomarkers for assessing the odds of influenza infection.

Mortality surveillance in the U.S. Army, 2005-2011.

PURPOSE: Mortality rates in the U.S. Army from 2005 to 2011 were examined over time and compared to the U.S. general population. METHOD: Cases were U.S. Army Soldiers (active duty or activated National Guard/Reserve) with dates of death between 2005 and 2011 and between 18 and 64 years of age in the Department of Defense Medical Mortality Registry. Age- and sex-adjusted annual mortality rates (AR) were calculated for each category of death and examined via linear regression. Proportions of underlying causes of death were also examined. RESULTS: The trend in AR in the U.S. Army significantly decreased for combat deaths, the average annual percent change (AAPC) = 15.2% decrease in the log of the rate (LAR); p = 0.04 and accident deaths, AAPC = 5.4% decrease in the LAR; p = 0.002 and significantly increased for suicides, AAPC = 10.6% increase in the LAR; p = 0.001. The trend in AR for suicides for the Army was significantly different compared to the U.S. general population, AAPC = 11.0% increase in the LAR; p < 0.001. CONCLUSIONS: Trends in rates of combat deaths and accident deaths declined although rates of suicides increased. The Army suicide rate increased in comparison to the United States. 70% of accident deaths were transportation related. Almost 70% of suicides and homicides were firearm related.

Prevalence of and risk factors for autopsy-determined atherosclerosis among US service members, 2001-2011.

CONTEXT: Autopsies of US service members killed in the Korean and Vietnam wars demonstrated that atherosclerotic changes in the coronary arteries can appear early in the second and third decades of life, long before ischemic heart disease becomes clinically apparent. OBJECTIVE: To estimate the current prevalence of coronary and aortic atherosclerosis in the US armed forces. DESIGN, SETTING, AND PARTICIPANTS: Cross-sectional study of all US service members who died of combat or unintentional injuries in support of Operations Enduring Freedom and Iraqi Freedom/New Dawn between October 2001 and August 2011 and whose cardiovascular autopsy reports were available at the time of data collection in January 2012. Prevalence of atherosclerosis was analyzed by various demographic characteristics and medical history. Classifications of coronary atherosclerosis severity were determined prior to data analysis and designed to provide consistency with previous military studies: minimal (fatty streaking only), moderate (10%-49% luminal narrowing of ≥1 vessel), and severe (≥50% narrowing of ≥1 vessel). MAIN OUTCOME MEASURES: Prevalence of coronary and aortic atherosclerosis in the US armed forces and by age, sex, self-reported race/ethnicity, education, occupation, service branch and component, military rank, body mass index at military entrance, and International Classification of Diseases, Ninth Revision, Clinical Modification, diagnoses of cardiovascular risk factors. RESULTS: Of the 3832 service members included in the analysis, the mean age was 25.9 years (range, 18-59 years) and 98.3% were male. The prevalence of any coronary atherosclerosis was 8.5% (95% CI, 7.6%-9.4%); severe coronary atherosclerosis was present in 2.3% (95% CI, 1.8%-2.7%), moderate in 4.7% (95% CI, 4.0%-5.3%), and minimal in 1.5% (95% CI, 1.1%-1.9%). Service members with atherosclerosis were significantly older (mean [SD] age, 30.5 [8.1] years) than those without (mean [SD] age, 25.3 [5.6] years; P < .001). Comparing atherosclerosis prevalence among with those with no cardiovascular risk factor diagnoses (11.1% [95% CI, 10.1%-12.1%]), there was a greater prevalence among those with a diagnosis of dyslipidemia (50.0% [95% CI, 30.3%-69.7%]; age-adjusted prevalence ratio [PR], 2.09 [95% CI, 1.43-3.06]), hypertension (43.6% [95% CI, 27.3%-59.9%]; age-adjusted PR, 1.88 [95% CI, 1.34-2.65]), or obesity (22.3% [95% CI, 15.9%-28.7%]; age-adjusted PR, 1.47 [95% CI, 1.10-1.96]), but smoking (14.1% [95% CI, 8.0%-20.2%]) was not significantly associated with a higher prevalence of atherosclerosis (age-adjusted PR, 1.12 [95% CI, 0.73-1.74]). CONCLUSION: Among deployed US service members who died of combat or unintentional injuries and received autopsies, the prevalence of atherosclerosis varied by age and cardiovascular risk factors.

Death on the battlefield (2001-2011): implications for the future of combat casualty care.

BACKGROUND: Critical evaluation of all aspects of combat casualty care, including mortality, with a special focus on the incidence and causes of potentially preventable deaths among US combat fatalities, is central to identifying gaps in knowledge, training, equipment, and execution of battlefield trauma care. The impetus to produce this analysis was to develop a comprehensive perspective of battlefield death, concentrating on deaths that occurred in the pre-medical treatment facility (pre-MTF) environment. METHODS: The Armed Forces Medical Examiner Service Mortality Surveillance Division was used to identify Operation Iraqi Freedom and Operation Enduring Freedom combat casualties from October 2001 to June 2011 who died from injury in the deployed environment. The autopsy records, perimortem records, photographs on file, and Mortality Trauma Registry of the Armed Forces Medical Examiner Service were used to compile mechanism of injury, cause of injury, medical intervention performed, Abbreviated Injury Scale (AIS) score, and Injury Severity Score (ISS) on all lethal injuries. All data were used by the expert panel for the conduct of the potential for injury survivability assessment of this study. RESULTS: For the study interval between October 2001 and June 2011, 4,596 battlefield fatalities were reviewed and analyzed. The stratification of mortality demonstrated that 87.3% of all injury mortality occurred in the pre-MTF environment. Of the pre-MTF deaths, 75.7% (n = 3,040) were classified as nonsurvivable, and 24.3% (n = 976) were deemed potentially survivable (PS). The injury/physiologic focus of PS acute mortality was largely associated with hemorrhage (90.9%). The site of lethal hemorrhage was truncal (67.3%), followed by junctional (19.2%) and peripheral-extremity (13.5%) hemorrhage. CONCLUSION: Most battlefield casualties died of their injuries before ever reaching a surgeon. As most pre-MTF deaths are nonsurvivable, mitigation strategies to impact outcomes in this population need to be directed toward injury prevention. To significantly impact the outcome of combat casualties with PS injury, strategies must be developed to mitigate hemorrhage and optimize airway management or reduce the time interval between the battlefield point of injury and surgical intervention.Understanding battlefield mortality is a vital component of the military trauma system. Emphasis on this analysis should be placed on trauma system optimization, evidence-based improvements in Tactical Combat Casualty Care guidelines, data-driven research, and development to remediate gaps in care and relevant training and equipment enhancements that will increase the survivability of the fighting force.