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Study Objective: In the early months of the coronavirus disease 2019 (COVID-19) pandemic and before vaccine availability, there were concerns that infected emergency department (ED) health care personnel could present a threat to the delivery of emergency medical care. We examined how the pandemic affected staffing levels and whether COVID-19 positive staff were potentially infectious at work in a cohort of US ED health care personnel in 2020., Methods: The COVID-19 Evaluation of Risks in Emergency Departments (Project COVERED) project was a multicenter prospective cohort study of US ED health care personnel conducted from May to December 2020. During surveillance, health care personnel completed weekly electronic surveys and underwent periodic serology and nasal reverse transcription polymerase chain reaction testing for SARS-CoV-2, and investigators captured weekly data on health care facility COVID-19 prevalence and health care personnel staffing. Surveys asked about symptoms, potential exposures, work attendance, personal protective equipment use, and behaviors., Results: We enrolled 1,673 health care personnel who completed 29,825 person weeks of surveillance. Eighty-nine (5.3%) health care personnel documented 90 (0.3%; 95% confidence interval [CI] 0.2% to 0.4%) person weeks of missed work related to documented or concerns for COVID-19 infection. Health care personnel experienced symptoms of COVID-19 during 1,256 (4.2%) person weeks and worked at least one shift whereas symptomatic during 1,042 (83.0%) of these periods. Seventy-five (4.5%) participants tested positive for SARS-CoV-2 during the surveillance period, including 43 (57.3%) who indicated they never experienced symptoms; 74 (98.7%; 95% CI 90.7% to 99.9%) infected health care personnel worked at least one shift during the initial period of infection, and 71 (94.7%) continued working until laboratory confirmation of their infection. Physician staffing was not associated with the facility or community COVID-19 levels within any time frame studied (Kendall tau's 0.02, 0.056, and 0.081 for no shift, one-week time shift, and 2-week time shift, respectively)., Conclusions: During the first wave of the pandemic, COVID-19 infections in ED health care personnel were infrequent, and the time lost from the workforce was minimal. Health care personnel frequently reported for work while infected with SARS-CoV-2 before laboratory confirmation. The ED staffing levels were poorly correlated with facility and community COVID-19 burden., (Copyright © 2024 American College of Emergency Physicians. Published by Elsevier Inc. All rights reserved.)

Background: The high mortality of systemic anthrax is likely a consequence of the severe central nervous system inflammation that occurs in anthrax meningitis. Effective treatment of such infections requires, at a minimum, adequate cerebrospinal fluid (CSF) antimicrobial concentrations., Methods: We reviewed English medical literature and regulatory documents to extract information on serum and CSF exposures for antimicrobials with in vitro activity against Bacillus anthracis. Using CSF pharmacokinetic exposures and in vitro B. anthracis susceptibility data, we used population pharmacokinetic modeling and Monte Carlo simulations to determine whether a specific antimicrobial dosage would likely achieve effective CSF antimicrobial activity in patients with normal to inflamed meninges (ie, an intact to markedly disrupted blood-brain barrier)., Results: The probability of microbiologic success at achievable antimicrobial dosages was high (≥95%) for ciprofloxacin, levofloxacin (500 mg every 12 hours), meropenem, imipenem/cilastatin, penicillin G, ampicillin, ampicillin/sulbactam, doxycycline, and minocycline; acceptable (90%-95%) for piperacillin/tazobactam and levofloxacin (750 mg every 24 hours); and low (<90%) for vancomycin, amikacin, clindamycin, and linezolid., Conclusions: Prompt empiric antimicrobial therapy of patients with suspected or confirmed anthrax meningitis may reduce the high morbidity and mortality. Our data support using several β-lactam-, fluoroquinolone-, and tetracycline-class antimicrobials as first-line and alternative agents for treatment of patients with anthrax meningitis; all should achieve effective microbiologic exposures. Our data suggest antimicrobials that should not be relied on to treat suspected or documented anthrax meningitis. Furthermore, the protein synthesis inhibitors clindamycin and linezolid can decrease toxin production and may be useful components of combination therapy., Competing Interests: Potential conflicts of interest . J. S. B. is supported by an NICHD grant (1 R01 HD095547-01). J. B. B. is supported by NIAID grants (R01 AI130185 and R01 AI136803). K. H., C. I., E. H., and P. Y. are career officers with the CDC. J. B. reports consulting fees from MicuRx Pharmaceuticals Inc, Aerovate Therapeutics, and Lupin and honorarium for a lecture under T32 (William Shafer, Emory) on antimicrobial pharmacology. A. W. K. reports stock from Pfizer, Johnson & Johnson, and AbbVie. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2024.)

This Report Updates Previous Cdc Guidelines and Recommendations on Preferred Prevention and Treatment Regimens Regarding Naturally Occurring Anthrax. Also Provided Are a Wide Range of Alternative Regimens to First-Line Antimicrobial Drugs for Use If Patients Have Contraindications or Intolerances or After a Wide-Area Aerosol Release of: Bacillus anthracis spores if resources become limited or a multidrug-resistant B. anthracis strain is used (Hendricks KA, Wright ME, Shadomy SV, et al.; Workgroup on Anthrax Clinical Guidelines. Centers for Disease Control and Prevention expert panel meetings on prevention and treatment of anthrax in adults. Emerg Infect Dis 2014;20:e130687; Meaney-Delman D, Rasmussen SA, Beigi RH, et al. Prophylaxis and treatment of anthrax in pregnant women. Obstet Gynecol 2013;122:885-900; Bradley JS, Peacock G, Krug SE, et al. Pediatric anthrax clinical management. Pediatrics 2014;133:e1411-36). Specifically, this report updates antimicrobial drug and antitoxin use for both postexposure prophylaxis (PEP) and treatment from these previous guidelines best practices and is based on systematic reviews of the literature regarding 1) in vitro antimicrobial drug activity against B. anthracis; 2) in vivo antimicrobial drug efficacy for PEP and treatment; 3) in vivo and human antitoxin efficacy for PEP, treatment, or both; and 4) human survival after antimicrobial drug PEP and treatment of localized anthrax, systemic anthrax, and anthrax meningitis., Changes From Previous Cdc Guidelines and Recommendations Include an Expanded List of Alternative Antimicrobial Drugs to Use When First-Line Antimicrobial Drugs Are Contraindicated or Not Tolerated or After a Bioterrorism Event When First-Line Antimicrobial Drugs Are Depleted or Ineffective Against a Genetically Engineered Resistant: B. anthracis strain. In addition, these updated guidelines include new recommendations regarding special considerations for the diagnosis and treatment of anthrax meningitis, including comorbid, social, and clinical predictors of anthrax meningitis. The previously published CDC guidelines and recommendations described potentially beneficial critical care measures and clinical assessment tools and procedures for persons with anthrax, which have not changed and are not addressed in this update. In addition, no changes were made to the Advisory Committee on Immunization Practices recommendations for use of anthrax vaccine (Bower WA, Schiffer J, Atmar RL, et al. Use of anthrax vaccine in the United States: recommendations of the Advisory Committee on Immunization Practices, 2019. MMWR Recomm Rep 2019;68[No. RR-4]:1-14). The updated guidelines in this report can be used by health care providers to prevent and treat anthrax and guide emergency preparedness officials and planners as they develop and update plans for a wide-area aerosol release of B. anthracis., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. CDC and contributors to this work disclose that they have no financial interests or other relationships with the manufacturers of commercial products, suppliers of commercial services, or commercial supporters that would unfairly influence these CDC recommendations with the following exceptions: Arthur Friedlander reports funding from the U.S. Department of Defense Threat Reduction Agency for research on anthrax vaccines and therapeutics. However, none of the vaccines or therapeutics were discussed for inclusion in the guidelines. Adolf W. Karchmer receives an honorarium for service on the data and safety monitoring board (tofacitinib) for Pfizer. Todd Semla’s spouse owns stock in Abbott. Both Pfizer and Abbott manufacture antimicrobial drugs included in the guidelines. No other potential conflicts of interest were disclosed.

Background and Objectives: The Food and Drug Administration expanded Emergency Use Authorization for use of Pfizer-BioNTech (BNT-162b2) coronavirus disease 2019 vaccine to include people ages 12 years and older on May 10, 2021. We describe adverse events observed during the first full year of the US coronavirus disease 2019 vaccination program for adolescents ages 12 to 17 years., Methods: We conducted descriptive analyses using data from 2 complementary US vaccine safety monitoring systems: v-safe, a voluntary smartphone-based system that monitors reactions and health impacts, and the Vaccine Adverse Event Reporting System (VAERS), the national spontaneous reporting system. We reviewed reports and calculated adverse event reporting rates using vaccine administration data., Results: Among 172 032 adolescents ages 12 to 17 years enrolled in v-safe, most reported reactions following BNT-162b2 were mild to moderate, most frequently reported on the day after vaccination, and more common after dose 2. VAERS received 20 240 adverse event reports; 91.5% were nonserious. Among adverse events of interest, we verified 40 cases of multisystem inflammation syndrome in children (1.2 cases per million vaccinations), 34 (85%) of which had evidence of prior severe acute respiratory syndrome coronavirus 2 infection; and 570 cases of myocarditis (17.7 cases per million vaccinations), most of whom (77%) reported symptom resolution at the time of report., Conclusions: During the first year BNT-162b2 was administered to adolescents ages 12 to 17 years, most reported adverse events were mild and appeared self-limited. Rates of myocarditis were lower than earlier reports. No new serious safety concerns were identified., (Copyright © 2023 by the American Academy of Pediatrics.)

Background: Bacillus anthracis is a high-priority threat agent because of its widespread availability, easy dissemination, and ability to cause substantial morbidity and mortality. Although timely and appropriate antimicrobial therapy can reduce morbidity and mortality, the role of adjunctive therapies continues to be explored., Methods: We searched 11 databases for articles that report use of anthrax antitoxins in treatment or prevention of systemic anthrax disease published through July 2019. We identified other data sources through reference search and communication with experts. We included English-language studies on antitoxin products with approval by the US Food and Drug Administration (FDA) for anthrax in humans, nonhuman primates, and rabbits. Two researchers independently reviewed studies for inclusion and abstracted relevant data., Results: We abstracted data from 12 publications and 2 case reports. All 3 FDA-approved anthrax antitoxins demonstrated significant improvement in survival as monotherapy over placebo in rabbits and nonhuman primates. No study found significant improvement in survival with combination antitoxin and antimicrobial therapy compared to antimicrobial monotherapy. Case reports and case series described 25 patients with systemic anthrax disease treated with antitoxins; 17 survived. Animal studies that used antitoxin monotherapy as postexposure prophylaxis (PEP) demonstrated significant improvement in survival over placebo, with greatest improvements coming with early administration., Conclusions: Limited human and animal evidence indicates that adjunctive antitoxin treatment may improve survival from systemic anthrax infection. Antitoxins may also provide an alternative therapy to antimicrobials for treatment or PEP during an intentional anthrax incident that could involve a multidrug-resistant B. anthracis strain., (Published by Oxford University Press on behalf of Infectious Diseases Society of America 2022. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

Background: We investigated patients with potential severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfection in the United States during May-July 2020., Methods: We conducted case finding for patients with potential SARS-CoV-2 reinfection through the Emerging Infections Network. Cases reported were screened for laboratory and clinical findings of potential reinfection followed by requests for medical records and laboratory specimens. Available medical records were abstracted to characterize patient demographics, comorbidities, clinical course, and laboratory test results. Submitted specimens underwent further testing, including reverse transcription polymerase chain reaction (RT-PCR), viral culture, whole genome sequencing, subgenomic RNA PCR, and testing for anti-SARS-CoV-2 total antibody., Results: Among 73 potential reinfection patients with available records, 30 patients had recurrent coronavirus disease 2019 (COVID-19) symptoms explained by alternative diagnoses with concurrent SARS-CoV-2 positive RT-PCR, 24 patients remained asymptomatic after recovery but had recurrent or persistent RT-PCR, and 19 patients had recurrent COVID-19 symptoms with concurrent SARS-CoV-2 positive RT-PCR but no alternative diagnoses. These 19 patients had symptom recurrence a median of 57 days after initial symptom onset (interquartile range: 47-76). Six of these patients had paired specimens available for further testing, but none had laboratory findings confirming reinfections. Testing of an additional 3 patients with recurrent symptoms and alternative diagnoses also did not confirm reinfection., Conclusions: We did not confirm SARS-CoV-2 reinfection within 90 days of the initial infection based on the clinical and laboratory characteristics of cases in this investigation. Our findings support current Centers for Disease Control and Prevention (CDC) guidance around quarantine and testing for patients who have recovered from COVID-19., (© The Author(s) 2021. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

During December 2018-February 2019, a multistate investigation identified 101 patients with vaccination-associated adverse events among an estimated 940 persons in Kentucky, Indiana, and Ohio who had received influenza; hepatitis A; pneumococcal; or tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccines at the workplace during September 11-November 28, 2018. These vaccines had been administered by staff members of a third-party health care company contracted by 24 businesses. Company A provided multiple vaccine types during workplace vaccination events across 54 locations in these adjoining states. Injection-site wound isolates from patients yielded Mycobacterium porcinum, a nontuberculous mycobacteria (NTM) species in the Mycobacterium fortuitum group; subtyping using pulsed-field gel electrophoresis of all 28 available isolates identified two closely related clusters. Site visits to company A and interviews with staff members identified inadequate hand hygiene, improper vaccine storage and handling, lack of appropriate medical record documentation, and lack of reporting to the Vaccine Adverse Event Reporting System (VAERS). Vaccination-associated adverse events can be prevented by training health care workers responsible for handling or administering vaccines in safe vaccine handling, administration, and storage practices, timely reporting of any suspected vaccination-associated adverse events to VAERS, and notifying public health authorities of any adverse event clusters., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Background: The Coronavirus Disease 2019 (COVID-19) pandemic, caused by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), evolved rapidly in the United States. This report describes the demographic, clinical, and epidemiologic characteristics of 544 U.S. persons under investigation (PUI) for COVID-19 with complete SARS-CoV-2 testing in the beginning stages of the pandemic from January 17 through February 29, 2020., Methods: In this surveillance cohort, the U.S. Centers for Disease Control and Prevention (CDC) provided consultation to public health and healthcare professionals to identify PUI for SARS-CoV-2 testing by quantitative real-time reverse-transcription PCR. Demographic, clinical, and epidemiologic characteristics of PUI were reported by public health and healthcare professionals during consultation with on-call CDC clinicians and subsequent submission of a CDC PUI Report Form. Characteristics of laboratory-negative and laboratory-positive persons were summarized as proportions for the period of January 17-February 29, and characteristics of all PUI were compared before and after February 12 using prevalence ratios., Results: A total of 36 PUI tested positive for SARS-CoV-2 and were classified as confirmed cases. Confirmed cases and PUI testing negative for SARS-CoV-2 had similar demographic, clinical, and epidemiologic characteristics. Consistent with changes in PUI evaluation criteria, 88% (13/15) of confirmed cases detected before February 12, 2020, reported travel from China. After February 12, 57% (12/21) of confirmed cases reported no known travel- or contact-related exposures., Conclusions: These findings can inform preparedness for future pandemics, including capacity for rapid expansion of novel diagnostic tests to accommodate broad surveillance strategies to assess community transmission, including potential contributions from asymptomatic and presymptomatic infections., Competing Interests: The authors have declared that no competing interests exist.

Nursing homes are high-risk settings for outbreaks of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19) (1,2). During the COVID-19 pandemic, U.S. health departments worked to improve infection prevention and control (IPC) practices in nursing homes to prevent outbreaks and limit the spread of COVID-19 in affected facilities; however, limited resources have hampered health departments' ability to rapidly provide IPC support to all nursing homes within their jurisdictions. Since 2008, the Centers for Medicare & Medicaid Services (CMS) has published health inspection results and quality ratings based on their Five-Star Quality Rating System for all CMS-certified nursing homes (3); these ratings might be associated with facility-level risk factors for COVID-19 outbreaks. On April 17, 2020, West Virginia became the first state to mandate and conduct COVID-19 testing for all nursing home residents and staff members to identify and reduce transmission of SARS-CoV-2 in these settings (4). West Virginia's census of nursing home outbreaks was used to examine associations between CMS star ratings and COVID-19 outbreaks. Outbreaks, defined as two or more cases within 14 days (with at least one resident case), were identified in 14 (11%) of 123 nursing homes. Compared with 1-star-rated (lowest rated) nursing homes, the odds of a COVID-19 outbreak were 87% lower among 2- to 3-star-rated facilities (adjusted odds ratio [aOR] = 0.13, 95% confidence interval [CI] = 0.03-0.54) and 94% lower among 4- to 5-star-rated facilities (aOR = 0.06, 95% CI = 0.006-0.39). Health departments could use star ratings to help identify priority nursing homes in their jurisdictions to inform the allocation of IPC resources. Efforts to mitigate outbreaks in high-risk nursing homes are necessary to reduce overall COVID-19 mortality and associated disparities. Moreover, such efforts should incorporate activities to improve the overall quality of life and care of nursing home residents and staff members and address the social and health inequities that have been recognized as a prominent feature of the COVID-19 pandemic in the United States (5)., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Background: Subdeltoid bursitis has been reported as an adverse event after intramuscular vaccination in the deltoid muscle. Most published case reports involved influenza vaccine., Objective: To estimate the risk for subdeltoid bursitis after influenza vaccination., Design: Retrospective cohort study., Setting: The Vaccine Safety Datalink, which contains health encounter data for 10.2 million members of 7 U.S. health care organizations., Patients: Persons who received an inactivated influenza vaccine during the 2016-2017 influenza season., Measurements: Potential incident cases were identified by searching administrative data for persons with a shoulder bursitis diagnostic code within 180 days after receiving an injectable influenza vaccine in the same arm. The date of reported bursitis symptom onset was abstracted from the medical record. A self-controlled risk interval analysis was used to calculate the incidence rate ratio of bursitis in a risk interval of 0 to 2 days after vaccination versus a control interval of 30 to 60 days, which represents the background rate. The attributable risk was also estimated., Results: The cohort included 2 943 493 vaccinated persons. Sixteen cases of symptom onset in the risk interval and 51 cases of symptom onset in the control interval were identified. The median age of persons in the risk interval was 57.5 years (range, 24 to 98 years), and 69% were women. The incidence rate ratio was 3.24 (95% CI, 1.85 to 5.68). The attributable risk was 7.78 (CI, 2.19 to 13.38) additional cases of bursitis per 1 million persons vaccinated., Limitation: The results may not be generalizable to vaccinations done in other types of health care settings., Conclusion: Although an increased risk for bursitis after vaccination was present, the absolute risk was small., Primary Funding Source: Centers for Disease Control and Prevention.

Background: California Senate Bill 277 (SB277) eliminated non-medical immunization exemptions. Since its introduction on February 19, 2015, the rate of medical exemptions in the state has increased. Filing a report to Vaccine Adverse Event Reporting System (VAERS) may be perceived as helpful in applying for a medical exemption. Our objective was to describe trends in reporting to VAERS from California coincident with introduction of SB277., Methods: This was a retrospective study of Californian children <18 years for whom a VAERS report was submitted between June 1, 2011 and July 31, 2018. VAERS is a national, passive, vaccine safety surveillance program co-managed by Centers for Disease Control and Prevention and FDA. The main outcomes were the proportion of VAERS reports submitted by parents (vs. other reporter types), time from immunization to VAERS report (reporting time), and adverse event type. We also performed spatial analysis, mapping reports pre- and post-mandate by county., Results: We identified 6703 VAERS reports from California during the study period. The proportion of reports received from parents increased after implementation of SB277, from 14% to 23%. The median reporting time by parents increased from 9 days in 2013-2014 to 31 days in 2016-2017. After the introduction of SB277, we observed an increase in reports describing behavioral and developmental symptoms among reports submitted >6 months after immunization., Conclusions: These recent changes in reporting patterns coincident with the introduction of SB277 may indicate that more parents are using VAERS to assist in applying for a medical exemption for their child.

Background: Since 2010, petitioner claims of shoulder injury related to vaccine administration (SIRVA) to the National Vaccine Injury Compensation Program (VICP) have been increasing., Objective: To conduct a scientific review of clinical characteristics of SIRVA petitions to the VICP., Methods: We queried the VICP's Injury Compensation System database for medical reports of alleged SIRVA and SIRVA-like injuries. Medical reports are summaries of petitioner claims and supporting documentation along with a VICP clinician reviewer diagnosis and assessment of criteria for concession. We conducted a descriptive analysis of SIRVA petitioner claims recommended by the VICP for concession as SIRVA injuries., Results: We identified 476 petitioner claims recommended for concession. Claims per year increased from two in 2011, the first full year in the analytic period, to 227 in 2016. Median age was 51 years, 82.8% were women, and median body mass index was 25.1 (range 17.0-48.9). Four hundred cases (84.0%) involved influenza vaccine. Pharmacy or store (n = 168; 35.3%) was the most common place of vaccination followed by doctor's office (n = 147; 30.9%). Fewer than half of cases reported a suspected administration error; 172 (36.1%) reported 'injection too high' on the arm. Shoulder pain, rotator cuff problems, and bursitis were common initial diagnoses. Most (80.0%) cases received physical or occupational therapy, 60.1% had at least one steroid injection, and 32.6% had surgery. Most (71.9%) healthcare providers who gave opinions on causality considered the injury was caused by vaccination. A minority (24.3%) of cases indicated that symptoms had resolved by the last visit available in medical records., Conclusions: Most conceded claims for SIRVA were in women and involved influenza vaccines. Injection too high on the arm could be a factor due to the risk of injecting into underlying non-muscular tissues. Healthcare providers should be aware of proper injection technique and anatomical landmarks when administering vaccines., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier Ltd. All rights reserved.)

Competing Interests: All authors have completed and submitted the ICMJE form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

Recombinant zoster vaccine (RZV; Shingrix), an adjuvanted glycoprotein vaccine, was licensed by the Food and Drug Administration (FDA) and recommended by the Advisory Committee on Immunization Practices for adults aged ≥50 years in October 2017 (1). The previously licensed live-attenuated zoster vaccine (ZVL; Zostavax) is recommended for adults aged ≥60 years. RZV is administered intramuscularly as a 2-dose series, with an interval of 2-6 months between doses. In prelicensure clinical trials, 85% of 6,773 vaccinated study participants reported local or systemic reactions after receiving RZV, with approximately 17% experiencing a grade 3 reaction (erythema or induration >3.5 inches or systemic symptoms that interfere with normal activity). However, rates of serious adverse events (i.e., hospitalization, prolongation of existing hospitalization, life-threatening illness, permanent disability, congenital anomaly or birth defect, or death) were similar in the RZV and placebo groups (2). After licensure, CDC and FDA began safety monitoring of RZV in the Vaccine Adverse Event Reporting System (VAERS) (3). During the first 8 months of use, when approximately 3.2 million RZV doses were distributed (GlaxoSmithKline, personal communication, 2018), VAERS received a total of 4,381 reports of adverse events, 130 (3.0%) of which were classified as serious. Commonly reported signs and symptoms included pyrexia (fever) (1,034; 23.6%), injection site pain (985; 22.5%), and injection site erythema (880; 20.1%). No unexpected patterns were detected in reports of adverse events or serious adverse events. Findings from early monitoring of RZV are consistent with the safety profile observed in prelicensure clinical trials., Competing Interests: All authors have completed and submitted the ICMJE form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

AbstractDengue virus infections have adversely impacted U.S. military operations since the Spanish-American War. The erosion of mission capabilities and lost duty days are underestimated. Appreciating the incidence and prevalence of dengue infections in U.S. military personnel is important to inform disease prevention strategies. Banked pre- and post-deployment serum samples from 1,000 U.S. military personnel with a single deployment to a dengue-endemic region were tested using a screening microneutralization assay to detect anti-dengue-virus-neutralizing antibodies. A total of 76 (7.6%) post-deployment samples were positive and 15 of the pre-deployment samples were negative. These figures represent an infection incidence of 1.5% and total of 17.6 seroconversions per 10,000 deployment months. These data represent a deploying military population with a relatively high background rate of dengue seropositivity, a low level of infection during deployment compared with background infection rates in the local populations, and the potential for worsening clinical attack rates with increased frequency of deployment. Additional studies are required to more clearly elucidate the dengue infection and disease risk in U.S. military personnel.