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Background Whether young adults who are infected with SARS-CoV-2 are at risk of subsequent infection is uncertain. We investigated the risk of subsequent SARS-CoV-2 infection among young adults seropositive for a previous infection. Methods This analysis was performed as part of the prospective COVID-19 Health Action Response for Marines study (CHARM). CHARM included predominantly male US Marine recruits, aged 18–20 years, following a 2-week unsupervised quarantine at home. After the home quarantine period, upon arrival at a Marine-supervised 2-week quarantine facility (college campus or hotel), participants were enrolled and were assessed for baseline SARS-CoV-2 IgG seropositivity, defined as a dilution of 1:150 or more on receptor-binding domain and full-length spike protein ELISA. Participants also completed a questionnaire consisting of demographic information, risk factors, reporting of 14 specific COVID-19-related symptoms or any other unspecified symptom, and brief medical history. SARS-CoV-2 infection was assessed by PCR at weeks 0, 1, and 2 of quarantine and participants completed a follow-up questionnaire, which included questions about the same COVID-19-related symptoms since the last study visit. Participants were excluded at this stage if they had a positive PCR test during quarantine. Participants who had three negative swab PCR results during quarantine and a baseline serum serology test at the beginning of the supervised quarantine that identified them as seronegative or seropositive for SARS-CoV-2 then went on to basic training at Marine Corps Recruit Depot—Parris Island. Three PCR tests were done at weeks 2, 4, and 6 in both seropositive and seronegative groups, along with the follow-up symptom questionnaire and baseline neutralising antibody titres on all subsequently infected seropositive and selected seropositive uninfected participants (prospective study period). Findings Between May 11, 2020, and Nov 2, 2020, we enrolled 3249 participants, of whom 3168 (98%) continued into the 2-week quarantine period. 3076 (95%) participants, 2825 (92%) of whom were men, were then followed up during the prospective study period after quarantine for 6 weeks. Among 189 seropositive participants, 19 (10%) had at least one positive PCR test for SARS-CoV-2 during the 6-week follow-up (1·1 cases per person-year). In contrast, 1079 (48%) of 2247 seronegative participants tested positive (6·2 cases per person-year). The incidence rate ratio was 0·18 (95% CI 0·11–0·28; p

Introduction Service women face female-specific challenges that present physiological and logistical burdens and may impact readiness. The stress of training can change menstrual patterns and symptoms, and limited access to hygienic, private facilities can hinder menstrual management. Therefore, suppressing menses with continuous hormonal contraception may be of interest. Materials and Methods The 9-item “Military Women’s Attitudes Toward Menstrual Suppression.” questionnaire was administered to female officers upon entry (baseline) and graduation (post) from a 6-month secondary training course. Respondents rated their attitudes about menstruation and the stress of training, the desire for menstrual suppression, and the logistical burden of menstruation on a 1 (strongly agree) through 5 (strongly disagree) scale. Wilcoxon Signed Rank Tests determined changes in the distribution of responses from baseline to post. Results Female officers (n = 108) completed baseline and post questionnaires (age 25.2 ± 0.3 years). At baseline, the majority disagreed/strongly disagreed that the stress of training “makes periods worse than usual” (n = 77, 71%), “increases menstrual symptoms and bleeding” (n = 77, 71%), or “magnifies premenstrual syndrome” (PMS; n = 69, 64%). Although 50% (n = 54) agreed/strongly agreed that “stopping periods while women are training is a good idea,” 37% (n = 40) disagreed/strongly disagreed. The majority agreed/strongly agreed that menstrual suppression would prevent “the worry about menstrual supplies” (n = 75, 70%) and “the inconvenience of having a period during training” (n = 69, 64%). Many agreed/strongly agreed that it is difficult to deal with periods during training because “there is no privacy” (n = 52, 48%), “the inability to find adequate facilities” (n = 70, 65%), and “the lack of opportunity to use adequate facilities” (n = 52, 48%). Opinions remained largely consistent from baseline to post. Conclusions The desire for menstrual suppression among service women during training is high. Military health care providers should be prepared to counsel service women about strategies to manage menstruation, including the efficacy of continuous hormonal contraception for menstrual suppression. Future studies investigating benefits or risks of continuous hormonal contraception for menstrual suppression in service women should inform the clinical recommendations.

Combat military and civilian law enforcement personnel may be exposed to repetitive low-intensity blast events during training and operations. Persons who use explosives to gain entry (i.e., breach) into buildings are known as “breachers” or dynamic entry personnel. Breachers operate under the guidance of established safety protocols, but despite these precautions, breachers who are exposed to low-level blast throughout their careers frequently report performance deficits and symptoms to healthcare providers. Although little is known about the etiology linking blast exposure to clinical symptoms in humans, animal studies demonstrate network-level changes in brain function, alterations in brain morphology, vascular and inflammatory changes, hearing loss, and even alterations in gene expression after repeated blast exposure. To explore whether similar effects occur in humans, we collected a comprehensive data battery from 20 experienced breachers exposed to blast throughout their careers and 14 military and law enforcement controls. This battery included neuropsychological assessments, blood biomarkers, and magnetic resonance imaging measures, including cortical thickness, diffusion tensor imaging of white matter, functional connectivity, and perfusion. To better understand the relationship between repetitive low-level blast exposure and behavioral and imaging differences in humans, we analyzed the data using similarity-driven multi-view linear reconstruction (SiMLR). SiMLR is specifically designed for multiple modality statistical integration using dimensionality-reduction techniques for studies with high-dimensional, yet sparse, data (i.e., low number of subjects and many data per subject). We identify significant group effects in these data spanning brain structure, function, and blood biomarkers.

Mild traumatic brain injury (mTBI) has been linked to mental health disorders (MHDs) and pituitary function alterations. Due to the complex relationship of mTBI, the neuroendocrine system, and MHDs, we propose that neuroendocrine dysfunction (NED) may play a role in negative long-term health outcomes. The goal of this study was to determine if blast-concussed service members (SMs) have a stronger likelihood of developing NED. We hypothesized that NED either pre- or post-injury is associated with poor mental and physical health outcomes. Serum samples from the Armed Forces Health Surveillance Branch were obtained from concussed (n = 59) and non-concussed (n = 72) SMs treated at the Concussion Restoration Care Center (CRCC) in Afghanistan. Serum was collected within 2 years prior to deployment and one or two times within 3 years following their CRCC visit. Samples were analyzed for luteinizing hormone (LH), testosterone, human growth hormone, cortisol, and prolactin to assess post-injury neuroendocrine function. Results indicate that SMs who incurred an mTBI exhibited long-term LH and testosterone deficiencies 3 years following injury compared to controls. Specifically, 47.6% of head-injured SMs displayed hypofunction in at least one of five hormones at 3 years post-injury. Anxiety disorders were the most common MHD observed in concussed SMs with hypopituitarism, while there was also a trend for SMs with chronic pituitary dysfunction to have MHD diagnoses. Findings indicate blast-related mTBI may be associated with long-term health outcomes following a period of incubation. Neuroendocrine screenings may increase treatment opportunities, inform rehabilitation strategies, and improve overall quality of life for patients.

Whether young adults who are infected with SARS-CoV-2 are at risk of subsequent infection is uncertain. We investigated the risk of subsequent SARS-CoV-2 infection among young adults seropositive for a previous infection.This analysis was performed as part of the prospective COVID-19 Health Action Response for Marines study (CHARM). CHARM included predominantly male US Marine recruits, aged 18-20 years, following a 2-week unsupervised quarantine at home. After the home quarantine period, upon arrival at a Marine-supervised 2-week quarantine facility (college campus or hotel), participants were enrolled and were assessed for baseline SARS-CoV-2 IgG seropositivity, defined as a dilution of 1:150 or more on receptor-binding domain and full-length spike protein ELISA. Participants also completed a questionnaire consisting of demographic information, risk factors, reporting of 14 specific COVID-19-related symptoms or any other unspecified symptom, and brief medical history. SARS-CoV-2 infection was assessed by PCR at weeks 0, 1, and 2 of quarantine and participants completed a follow-up questionnaire, which included questions about the same COVID-19-related symptoms since the last study visit. Participants were excluded at this stage if they had a positive PCR test during quarantine. Participants who had three negative swab PCR results during quarantine and a baseline serum serology test at the beginning of the supervised quarantine that identified them as seronegative or seropositive for SARS-CoV-2 then went on to basic training at Marine Corps Recruit Depot-Parris Island. Three PCR tests were done at weeks 2, 4, and 6 in both seropositive and seronegative groups, along with the follow-up symptom questionnaire and baseline neutralising antibody titres on all subsequently infected seropositive and selected seropositive uninfected participants (prospective study period).Between May 11, 2020, and Nov 2, 2020, we enrolled 3249 participants, of whom 3168 (98%) continued into the 2-week quarantine period. 3076 (95%) participants, 2825 (92%) of whom were men, were then followed up during the prospective study period after quarantine for 6 weeks. Among 189 seropositive participants, 19 (10%) had at least one positive PCR test for SARS-CoV-2 during the 6-week follow-up (1·1 cases per person-year). In contrast, 1079 (48%) of 2247 seronegative participants tested positive (6·2 cases per person-year). The incidence rate ratio was 0·18 (95% CI 0·11-0·28; p0·001). Among seropositive recruits, infection was more likely with lower baseline full-length spike protein IgG titres than in those with higher baseline full-length spike protein IgG titres (hazard ratio 0·45 [95% CI 0·32-0·65]; p0·001). Infected seropositive participants had viral loads that were about 10-times lower than those of infected seronegative participants (ORF1ab gene cycle threshold difference 3·95 [95% CI 1·23-6·67]; p=0·004). Among seropositive participants, baseline neutralising titres were detected in 45 (83%) of 54 uninfected and in six (32%) of 19 infected participants during the 6 weeks of observation (ID50 difference p0·0001).Seropositive young adults had about one-fifth the risk of subsequent infection compared with seronegative individuals. Although antibodies induced by initial infection are largely protective, they do not guarantee effective SARS-CoV-2 neutralisation activity or immunity against subsequent infection. These findings might be relevant for optimisation of mass vaccination strategies.Defense Health Agency and Defense Advanced Research Projects Agency.

In a study of US Marine recruits, seroprevalence of severe acute respiratory syndrome coronavirus 2 IgG was 9.0%. Hispanic and non-Hispanic Black participants and participants from states affected earlier in the pandemic had higher seropositivity rates. These results suggest the need for targeted public health strategies among young adults at increased risk for infection.

Background: The risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) subsequent infection among seropositive young adults was studied prospectively. Methods: The study population comprised 3,249 predominantly male, 18-20-year-old Marine recruits. Upon arrival at a Marine-supervised two-week quarantine, participants were assessed for baseline SARS-CoV-2 IgG seropositivity, defined as a 1:150 dilution or greater on receptor binding domain and full-length spike protein enzyme-linked immunosorbent (ELISA) assays. SARS-CoV-2 infection was assessed by PCR at initiation, middle and end of the quarantine. After appropriate exclusions, including participants with a positive PCR during quarantine, we performed three biweekly PCR tests in both seropositive and in seronegative groups once recruits left quarantine and entered basic training and baseline neutralizing antibody titers on all subsequently infected seropositive and selected seropositive uninfected participants. Findings: Among 189 seropositive participants, 19 (10.1%) had at least one positive PCR test for SARS-CoV-2 during the six-week follow-up (1.1 cases per person-year). In contrast, 1,079 (48.0%) of the 2,247 seronegative participants tested positive (6.2 cases per person-year). The incidence rate ratio was 0.18 (95% CI 0.11-0.28, p

As NK cells are critical for control of viral infections, we tested the hypothesis that individuals with asymptomatic SARS-CoV-2 infection have greater NK cell frequencies prior to infection than individuals with mild, symptomatic infection. Marine recruits who elected to participate in the COVID-19 Health Action Response for Marines (CHARM) study were prospectively followed for two months twice weekly using PCR testing for SARS-CoV-2 infection and symptom questionnaires. Peripheral blood mononuclear cells obtained prior to infection during enrollment in the study and at various time points post-infection from 47 participants diagnosed with asymptomatic infection and 49 with symptomatic infection were analyzed by flow cytometry for frequencies of total NK cells, NK cell subsets, and surface expression of activating and inhibitory receptors. Consistent with our hypothesis, frequencies of total (CD3−CD14−CD19−CD56+) NK cells were significantly greater at baseline in asymptomatic compared to symptomatic participants (10.4% vs 8.3%, p = 0.015). This difference was due to increased frequencies of mature (CD56dimCD16+) NK cells in asymptomatic individuals (76.3% vs 69.8%, p = 0.049). No differences were observed in baseline frequencies of immature (CD56brightCD16−) or adaptive (CD56dimCD16+NKG2C+CD57+) NK cells, or in surface expression of activating (NKG2C, NKG2D) or inhibitory (NKG2A, KIR2DL1, KIR2Dl2/L3/S2, KIR3DL1) receptors. Frequencies of total and mature NK cells decreased significantly post-infection, reaching a nadir at 3–4 weeks. In contrast, frequencies of immature NK cells increased by 4 weeks. These results suggest that NK cells may play a protective role against symptomatic SARS-CoV-2 infection. This work was supported by a grant from the Defense Health Agency through the Naval Medical Research Center (work unit number 9700130).

BACKGROUND A number of pharmaceutical agents have limited water solubility and are therefore often prepared in a lipid emulsion. Emulsion renders plasma opaque and this could interfere with the accuracy of some standardized laboratory measurements, especially for optical or mechanical based assays. We determined the interference on some laboratory diagnostic values of blood specimens after propofol addition in vitro as well as in vivo when infused into swine. METHODS In vitro, laboratory parameters were measured immediately after mixing swine blood diluted with increasing amounts of propofol emulsion in the range of 3 to 23%, v/v. The contact time of a 9% v/v mixture of blood and propofol was also examined over a 3-hours period. Saline-diluted samples served as controls. Cellular volume, hematocrit, hemoglobin, potassium, and coagulation were measured with various instruments. In addition, similar parameters were analyzed from swine blood following a 9 - 10 hours infusion with propofol/fentanyl compared to infusion with ketamine/midazolam. RESULTS In vitro, blood cell volume increased immediately upon contact with a mixture exceeding 6% propofol. Above 9% of the mixture, the cellular volume expanded significantly with extracellular K+ leakage. Hematocrit increased but the hemoglobin was dependent on the instrument type. Coagulation was altered when the emulsion was present. Interestingly, in vivo these effects were significant less pronounced in blood collected from experimental swine under total intravenous propofol anesthesia, but they departed from water-based anesthesia in control swine. CONCLUSIONS The in vitro studies indicate that results from certain assays of blood samples rich in lipid emulsion may not be accurate due to interference with optical, mechanical or ion selective electrode methodology. Although in vivo samples may be less impacted, there is still a risk of deviation from accuracy.

BACKGROUND: Hemorrhage and traumatic brain injury can be lethal if left unattended. The transportation of severely wounded combat casualties from the battlefield to higher level of care via aeromedical evacuation (AE) may result in unintended complications. This could become a serious concern at the time of evacuation of mass casualties or for prolonged field care scenarios with limited resources.METHODS: Following instrumentation (t1), anesthetized Sprague-Dawley rats were injured or not [75-kPa blast and 30% estimated blood-volume controlled hemorrhage] (t2). After 15 min, all rats were resuscitated with saline. During the simulated 3-h evacuation, 8000 ft (2440 m) vs. sea-level heart rate, temperature, and oxygenation (Spo2) were continuously recorded. One group of rats was euthanized immediately after evacuation (t3) and another after a 72-h recovery period (t4). Hematology and metabolic levels were measured at t1, t2, t3, and t4.RESULTS: Survival was 100% in control-uninjured animals, 83% in injured animals under normobaria, and significantly reduced to 50% under hypobaria. This AE setting resulted in significantly lower hemodynamics, thermoregulation, and oxygenation parameters in the animals under hypobaria than those under normobaria. The initial lower mean arterial pressure (MAP) with the reduced oxygen level before AE were critical factors for the survival of injured animals. We observed a general increase of white blood cells and platelet ability to aggregate at t4 in all experimental groups.CONCLUSION: Physiological parameters were affected during aeromedical evacuation in all groups. This was worsened for injured animals with MAP less than 60 mmHg associated with low Spo2 in a simulated aeromedical evacuation. This represented a high risk of mortality for severely polytraumatized animals.Arnaud F, Pappas G, Maudlin-Jeronimo E, Goforth C. Simulated aeromedical evacuation in a polytrauma rat model. Aerosp Med Hum Perform. 2019; 90(12):1016–1025.

Mild traumatic brain injury (mTBI) is a risk for military personnel due to blast overpressures, which may result from a variety of sources, including artillery and improvised explosive devices. Much research has gone into the search for a biomarker to identify patients with a TBI. The FDA recently identified two proteins, glial fibrillary acidic protein (GFAP) and ubiquitin C-terminal hydrolase-L1 (UCH-L1), as biomarkers to evaluate suspected brain injury. Our group previously observed changes in UCH-L1 in a military population exposed to repeated blast. In our current study we assessed GFAP protein levels in a military population exposed to repeated blast during a 2-week training protocol. We observed GFAP levels were reduced in the moderate blast cases on days 6 and 7 during the training. Specifically, moderate blast cases showed a 24.07% reduction from baseline on day 6 and a 29.61% reduction on day 7. Further, GFAP levels were negatively correlated with cumulative blast experienced during training and with duration of military service. We observed that repeated blast exposure at low levels may impact acute changes in GFAP. Additionally subacute cumulative blast exposure or duration of service was also a factor in influencing GFAP levels.

The first of its kind, this study determined whether blast exposure interacts with genetic variant 5HTTLPR to predict posttraumatic stress (PTS) symptoms in 78 military explosives operators. In all models, blast-exposed 5HTTLPR S carriers registered definitively higher PTS symptoms in comparison to non-exposed S carriers, as well as exposed and non-exposed LL carriers (all p 0.01). All findings were robust to confounding influences of age and traumatic brain injury diagnosis. Not only is blast exposure prevalent in EOD personnel, but it also interacts with genetic predisposition to predict trauma symptoms in this unique, at-risk military population.

Background Aeromedical evacuation (AE) is often used as a rapid and effective way to evacuate patients. However, little is known about the possible effects of AE on patients with blast and traumatic brain injury. In the current study, we used blast overpressure (BOP) as a method to introduce traumatic brain injury in rats and investigated the effects of hypobaria during AE on histology and inflammatory response. Methods Animals were exposed to a 12-hour flight 2 days after BOP and euthanized 48 hours after flight. Control animals were kept at normobaria. Results Overall, BOP animals exposed to flight demonstrated higher histopathologic injury scores as compared to control animals in lungs, brain, kidney, heart, and intestine. The BOP animals exposed to normobaria exhibited a proinflammatory response compared to those that were not blasted, an observation that was not seen in BOP animals exposed to hypobaria. Conclusion These data suggest that AE 48 hours post blast may lead to impairment in the inflammatory process and worsening of long-term outcomes. Level of evidence Animal research, level II.

Trauma endures as the leading cause of death worldwide, and most deaths occur in the first 24 hours after initial injury as a result of hemorrhage. Historically, about 90% of battlefield deaths occur before the injured person arrives at a theater hospital, and most are due to noncompressible hemorrhage of the torso. Resuscitative endovascular balloon occlusion of the aorta is an evolving technique to quickly place a balloon into the thoracic or abdominal aorta to efficiently block blood flow to distal circulation. Maneuvers, such as resuscitative endovascular balloon occlusion of the aorta, to control endovascular hemorrhage offer a potential intervention to control noncompressible hemorrhage. This technique can be performed percutaneously or open in prehospital environments to restore hemodynamic functions and serve as a survival bridge until the patient is delivered to a treatment facility for definitive surgical hemostasis. This article describes the indications, complications, and application of resuscitative endovascular balloon occlusion of the aorta to military and civilian aeromedical transport.

Uncontrolled hemorrhage and exsanguination are the leading cause of preventable death, and resuscitative therapy is a critical component for survival. In various combinations, fresh whole blood, blood components, colloids, and crystalloids have all been staples of trauma care. The use of fresh whole blood is a well-established military practice that has saved the lives of thousands of American and coalition military personnel. Civilian use of fresh whole blood is far less established owing to the wide availability of individual blood components. However, this highly tailored blood supply is vulnerable to both natural and man-made disasters. In the event of such disruption, such as a major hurricane, it may be necessary for civilian hospitals to rapidly enact a fresh whole blood program. Therefore, the aim of this article is to review the current use of blood therapy for trauma resuscitation, the US military’s approach to fresh whole blood, and how maintaining a civilian capacity for fresh whole blood collection in the event of future man-made and natural disasters is key to promoting survival from trauma.

Although exertional heat stroke is considered a preventable condition, this life-threatening emergency affects hundreds of military personnel annually. Because heat stroke is preventable, it is important that Navy critical care nurses rapidly recognize and treat heat stroke casualties. Combined intrinsic and extrinsic risk factors can quickly lead to heat stroke if not recognized by deployed critical care nurses and other first responders. In addition to initial critical care nursing interventions, such as establishing intravenous access, determining body core temperature, and assessing hemodynamic status, aggressive cooling measures should be initiated immediately. The most important determinant in heat stroke outcome is the amount of time that patients sustain hyperthermia. Heat stroke survival approaches 100% when evidence-based cooling guidelines are followed, but mortality from heat stroke is a significant risk when care is delayed. Navy critical care and other military nurses should be aware of targeted assessments and cooling interventions when heat stroke is suspected during military operations. (Critical Care Nurse. 2015;35[1]:52–59)

Heat-related illness is a primary threat to unit readiness, and individual body armor (IBA) cooling devices represent one potential solution.To quantify research findings of active and passive cooling devices designed to reduce physiological strain while wearing IBA during strenuous tasks using a systematic review approach.Literature searches were performed in multiple databases using the key words "physiological," "body armor," "military," "cooling," and "thermal." Two independent reviewers appraised methodological quality using a modified Downs and Black Quality Index. Physiological outcomes were tabulated and effect sizes were calculated when appropriate.The search yielded 733 citations, with nine articles fitting our inclusion criteria: six articles with active and three articles with passive cooling devices. Results reveal a moderate level of methodological quality. On average, all six active IBA cooling device studies compared to controls (IBA only) reported decreases in one or more measures of physiological strain-core and skin temperature, heart rate. Conversely, passive cooling device effects were negligible.Active cooling devices may decrease the physiological strain associated with wearing IBA in hot environments. Further development of optimal cooling strategies to reduce physiological strain during operations where IBA is required is warranted.

A personal account of a U.S. Navy nurse's experiences with a victim of trauma in Iraq is presented.