Occupational and industry prevalence of new long-term symptoms within American Red Cross blood donors with and without history of SARS-CoV-2 infection.

PURPOSE: Limited information is known about the burden of Long COVID by occupation and industry. This study compares the occurrence of self-reported new long-term symptoms lasting 4 weeks or longer among blood donors with and without prior SARS-CoV-2 infection by occupation and industry. METHODS: The American Red Cross invited blood donors 18 years and older who donated during May 4-December 31, 2021 to participate in online surveys. New long-term symptoms lasting 4 weeks or longer were assessed by self-reported occurrence of any of 35 symptoms since March 2020. SARS-CoV-2 infection status was determined by serological testing and self-report. We describe the prevalence of new long-term symptoms by SARS-CoV-2 infection status. We calculate the difference in reported new long-term symptoms by SARS-CoV-2 infection status within occupation and industry categories. RESULTS: Data were collected from 27,907 employed adults - 9763 were previously infected and 18,234 were never infected with SARS-CoV-2. New long-term symptoms were more prevalent among those previously infected compared to the never-infected respondents (45% vs 24%, p < 0.05). Among all respondents, new long-term symptoms by occupation ranged from 26% (installation, maintenance, and repair) to 41% (healthcare support) and by industry ranged from 26% (mining) to 55% (accommodation and food services). New long-term neurological and other symptoms were commonly reported by those previously infected with SARS-CoV-2. DISCUSSION: New long-term symptoms are more prevalent among certain occupation and industry groups, which likely reflects differential exposure to SARS-CoV-2. These findings highlight potential need for workplace accommodations in a variety of occupational settings to address new long-term symptoms.

Prevalence of SARS-CoV-2 infection among US blood donors by industry, May-December 2021.

BACKGROUND: Work is a social determinant of health that is often overlooked. There are major work-related differences in the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and death, but there have been few analyses of infection rates across industry groups. To date, only one national assessment of SARS-CoV-2 infection prevalence by industry based on self-report has been completed. No study has looked at seroprevalence of COVID-19 by industry. METHODS: During May-December 2021, blood donors with SARS-CoV-2 antinucleocapsid testing were sent an electronic survey about their work. Free-text industry responses were classified using the North American Industry Classification System. We estimated seroprevalence and 95% confidence intervals (CIs) of SARS-CoV-2 infection by industry. RESULTS: Of 57,726 donors, 7040 (12%, 95% CI: 11.9%-12.5%) had prior SARS-CoV-2 infection. Seroprevalence was highest among Accommodation & Food Services (19.3%, 95% CI: 17.1%-21.6%), Mining, Quarrying, and Oil and Gas Extraction (19.2%, 95% CI: 12.8%-27.8%), Healthcare & Social Assistance (15.6%, 95% CI: 14.9%-16.4%), and Construction (14.7%, 95% CI: 13.1%-16.3%). Seroprevalence was lowest among Management of Companies & Enterprises (6.5%, 95% CI: 3.5%-11.5%), Professional Scientific & Technical Services (8.4%, 95% CI: 7.7%-9.0%), and Information (9.9%, 95% CI: 8.5%-11.5%). CONCLUSIONS: While workers in all industries had serologic evidence of SARS-CoV-2 infection, certain sectors were disproportionately impacted. Disease surveillance systems should routinely collect work characteristics so public health and industry leaders can address health disparities using sector-specific policies.

Distribution of COVID-19 mitigation measures by industry and work arrangement-US blood donors, May 2021-December 2021.

OBJECTIVE: To describe coronavirus disease 2019 (COVID-19) mitigation measures in workplaces of employed US blood donors by industry and work arrangement. METHODS: During May-December 2021, blood donors responded to a survey; we describe the distribution of reported workplace mitigation measures by industry and work arrangement, organized using the hierarchy of controls. RESULTS: Of 53,433 respondents representing 21 industries, ventilation upgrades were reported by 4%-38% of respondents (overall: 20%); telework access ranged from 14%-80% (53% overall). Requiring masks (overall: 84%; range: 40%-94%), physical distancing (77%; 51%-86%), paid leave for illness (70%; 38%-87%), and encouraging vaccination (61%; 33%-80%) were common. Independent workers reported fewer mitigation measures than those in traditional employment settings. CONCLUSIONS: Mitigation measures varied by industry and work arrangement. Some mitigation measures may be challenging to implement or irrelevant in certain industries, supporting the idea that mitigation is not a one-size-fits-all strategy. POLICY IMPLICATIONS: Tailored strategies to mitigate workplace risks of disease transmission are vital. Strategies should rely on effective methods for identifying workplace controls (e.g., through the hierarchy of controls) and account for industry-specific characteristics and workplace environments.

Occupations Associated With Severe Acute Respiratory Syndrome Coronavirus 2 Infection and Vaccination, US Blood Donors, May 2021-December 2021.

BACKGROUND: There are limited data on the risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in the United States by occupation. We identified occupations at higher risk for prior SARS-CoV-2 infection as defined by the presence of infection-induced antibodies among US blood donors. METHODS: Using a nested case-control study design, blood donors during May-December 2021 with anti-nucleocapsid (anti-N) testing were sent an electronic survey on employment status, vaccination, and occupation. The association between previous SARS-CoV-2 infection and occupation-specific in-person work was estimated using multivariable logistic regression adjusting for sex, age, month of donation, race and ethnicity, education, vaccination, and telework. RESULTS: Among 85 986 included survey respondents, 9504 (11.1%) were anti-N reactive. Healthcare support (20.3%), protective service (19.9%), and food preparation and serving related occupations (19.7%) had the highest proportion of prior infection. After adjustment, prior SARS-CoV-2 infection was associated with healthcare practitioners (adjusted odds ratio [aOR], 2.10; 95% confidence interval [CI], 1.74-2.54) and healthcare support (aOR, 1.82; 95% CI, 1.39-2.40) occupations compared with computer and mathematical occupations as the referent group. Lack of coronavirus disease 2019 vaccination (aOR, 16.13; 95% CI, 15.01-17.34) and never teleworking (aOR, 1.17; 95% CI, 1.05-1.30) were also independently associated with prior SARS-CoV-2 infection. Construction and extraction occupations had the highest proportion of unvaccinated workers (30.5%). CONCLUSIONS: Workers in healthcare, protective services, and food preparation had the highest prevalence of prior SARS-CoV-2 infection. Occupational risks for SARS-CoV-2 infection remained after adjusting for vaccination, telework, and demographic factors. These findings underscore the need for mitigation measures and personal protection in healthcare settings and other workplaces.

Trajectory and Demographic Correlates of Antibodies to SARS-CoV-2 Nucleocapsid in Recently Infected Blood Donors, United States.

We evaluated antibodies to the nucleocapsid protein of SARS-CoV-2 in a large cohort of blood donors in the United States who were recently infected with the virus. Antibodies to the nucleocapsid protein of SARS-CoV-2 indicate previous infection but are subject to waning, potentially affecting epidemiologic studies. We longitudinally evaluated a cohort of 19,323 blood donors who had evidence of recent infection by using a widely available serologic test to determine the dynamics of such waning. We analyzed overall signal-to-cutoff values for 48,330 donations (average 2.5 donations/person) that had an average observation period of 102 days. The observed peak signal-to-cutoff value varied widely, but the waning rate was consistent across the range, with a half-life of 122 days. Within the cohort, only 0.75% of persons became seronegative. Factors predictive of higher peak values and longer time to seroreversion included increasing age, male sex, higher body mass index, and non-Caucasian race.

Low risk of human T-lymphotropic virus infection in U.S. blood donors; Is it time to consider a one-time selective testing approach?

BACKGROUND: U.S. blood donors are tested at each donation for human T-lymphotropic virus (HTLV) antibodies. Depending on donor incidence and other mitigation/removal technologies, a strategy of one-time selective donor testing should be considered. METHODS: Antibody seroprevalence was calculated for HTLV-confirmed-positive American Red Cross allogeneic blood donors from 2008 to 2021. Incidence was estimated for seven 2-year time periods using confirmed-positive repeat donors having seroconverted in 730 days. Leukoreduction failure rates were obtained from internal data from July 1, 2008-June 30, 2021. Residual risks were calculated using a 51-day window period. RESULTS: Between 2008 and 2021, >75 million donations (>18 million donors) yielded 1550 HTLV seropositives. HTLV seroprevalence was 2.05 antibody-positives per 100,000 donations (0.77 HTLV-1, 1.03 HTLV-2, 0.24 HTLV-1/2), and 10.32 per 100,000 among >13.9 million first-time donors. Seroprevalence differed significantly by virus type, sex, age, race/ethnicity, donor status, and U.S. census region. Over 14 years and 24.8 million person-years of observation, 57 incident donors were identified (25 HTLV-1, 23 HTLV-2, and 9 HTLV-1/2). Incidence decreased from 0.30 (13 cases) in 2008-2009 to 0.25 (7 cases) in 2020-2021. Female donors accounted for most incident cases (47 vs. 10 males). In the last 2-year reporting period, the residual risk was 1 per 2.8 million donations and 1 per 3.3 billion donations when coupled with successful leukoreduction (0.085% failure rate). CONCLUSIONS: HTLV donation seroprevalence for the years 2008-2021 varied by virus type and donor characteristics. Low HTLV residual risk and use of leukoreduction processes support the conclusion that a selective one-time donor testing strategy should be considered.

Population-Weighted Seroprevalence From Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Infection, Vaccination, and Hybrid Immunity Among US Blood Donations From January to December 2021.

BACKGROUND: Previous severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and coronavirus disease 2019 (COVID-19) vaccination, independently and combined ("hybrid immunity"), result in partial protection from subsequent infection and strong protection from severe disease. Proportions of the US population who have been infected, vaccinated, or have hybrid immunity remain unclear, posing a challenge for assessing effective pandemic mitigation strategies. METHODS: In this serial cross-sectional study, nationwide blood donor specimens collected during January-December 2021 were tested for anti-spike and anti-nucleocapsid antibodies, and donor COVID-19 vaccination history of ≥1 dose was collected. Monthly seroprevalence induced from SARS-CoV-2 infection, COVID-19 vaccination, or both, were estimated. Estimates were weighted to account for demographic differences from the general population and were compared temporally and by demographic factors. RESULTS: Overall, 1 123 855 blood samples were assayed. From January to December 2021, the weighted percentage of donations with seropositivity changed as follows: seropositivity due to vaccination without previous infection, increase from 3.5% (95% confidence interval, 3.4%-3.7%) to 64.0%, (63.5%-64.5%); seropositivity due to previous infection without vaccination, decrease from 15.6% (15.2%-16.0%) to 11.7% (11.4%-12.0%); and seropositivity due to hybrid immunity, increase from 0.7% (0.6%-0.7%) to 18.9% (18.5%-19.3%). Combined seroprevalence from infection, vaccination, or both increased from 19.8% (19.3%-20.2%) to 94.5% (93.5%-94.0%). Infection- and vaccination-induced antibody responses varied significantly by age, race-ethnicity, and region, but not by sex. CONCLUSIONS: Our results indicate substantial increases in population humoral immunity from SARS-CoV-2 infection, COVID-19 vaccination, and hybrid immunity during 2021. These findings are important to consider in future COVID-19 studies and long-term pandemic mitigation efforts.

How do we form and coordinate a national serosurvey of SARS-CoV-2 within the blood collection industry?

BACKGROUND: A national serosurvey of U.S. blood donors conducted in partnership with the Centers for Disease Control and Prevention (CDC) was initiated to estimate the prevalence of SARS-CoV-2 infections and vaccinations. METHODS: Beginning in July 2020, the Nationwide Blood Donor Seroprevalence Study collaborated with multiple blood collection organizations, testing labs, and leadership from government partners to capture, test, and analyze approximately 150,000 blood donation specimens per month in a repeated, cross-sectional seroprevalence survey. RESULTS: A CDC website (https://covid.cdc.gov/covid-data-tracker/#nationwide-blood-donor-seroprevalence) provided stratified, population-level results to public health professionals and the general public. DISCUSSION: The study adapted operations as the pandemic evolved, changing specimen flow and testing algorithms, and collecting additional data elements in response to changing policies on universal blood donation screening and administration of SARS-CoV-2 spike-based vaccines. The national serosurvey demonstrated the utility of serosurveillance testing of residual blood donations and highlighted the role of the blood collection industry in public-private partnerships during a public health emergency.

Two Congener-specific Models Estimate PCB TEQ Hazard to American Mink (Neovison vison) Living near a Western New York Creek.

We present two models to monitor the health of ecosystems by assessing hazard from a persistent organic compound to a top predator species. Our diet model predicts the dietary exposure of American Mink (Neovison vison) to PCB toxic equivalents (TEQ) by combining concentrations in their prey using weighted average proportions consistent with literature-based mink diets. Our bioaccumulation model predicts the dietary exposure of mink to PCB TEQ based on each congener's total concentration in water (dissolved plus particulate fractions), the octanal/water partition coefficient (log Kow) of the compound, and the trophic levels of prey taxa. Both models predict mink dietary concentrations which can be directly compared with each other and with lowest observable adverse effects concentrations (LOAECs) to assess chronic and acute hazards of PCB TEQ to mink. By our choice of certain parameters in the bioaccumulation model, we forced it to match the diet model within less than 5% for Eighteenmile Creek in western New York State. When the two models were used for a similar creek about 25 km away, the differences in their predictions were of the same magnitude.

HIV, HCV, and HBV incidence and residual risk in US blood donors before and after implementation of the 12-month deferral policy for men who have sex with men.

BACKGROUND: In December 2015, the men who have sex with men (MSM) deferral was reduced to 12 months in the United States. We compared human immunodeficiency virus (HIV), hepatitis C virus (HCV), and hepatitis B virus (HBV) incidence and residual risk before and after this policy change using data from >50% of the US blood supply. STUDY DESIGN AND METHODS: Three estimation intervals from the Transfusion-Transmissible Infections Monitoring System were compared: 15-months pre- and two consecutive, nonoverlapping 15-month post-MSM deferral implementation. Repeat, first-time, and weighted all-donor incidences were estimated. Residual risk was calculated for all incidence estimates using the incidence/window-period method. RESULTS: HIV repeat donor incidence was 1.57 per 100 000 person-years (phtpy) in the second 15-month post change and not significantly different from pre-MSM incidence of 2.19 phtpy. Similar values were seen for HCV (1.49 phtpy vs 1.46 phtpy) and HBV (1.14 phtpy vs 0.97 phtpy). In some cases, higher estimated incidence, but without significant change from pre-MSM to the second post change period occurred for males and first-time donors (eg, first-time donors, second post change period: 6.12 phtpy HIV, 6.41 phtpy HCV and 5.34 phtpy HBV). Estimated per donation residual risk was 1:1.6 million for HIV, 1:2.0 million for HCV and 1:1.0 million for HBV based on weighted incidence for all donors. CONCLUSIONS: Repeat, first-time, and overall donor incidence did not vary significantly comparing pre-MSM to either of the post-MSM estimation intervals. Residual risk estimates vary by study, but all yield residual risks in the United States of ≤1 per million, and thus far have not shown increasing risk with the 12-month MSM policy change.

Prevalence, risk factors, and ferritin testing to mitigate iron depletion in male plateletpheresis donors.

BACKGROUND: Most single-donor platelet (SDP) donors transition to plateletpheresis after prior red blood cell (RBC) donation. Recruitment may follow identification of a high platelet count, a marker associated with iron depletion (ID). SDP donors may have underrecognized risk for iron depletion. STUDY DESIGN AND METHODS: To assess the prevalence of ID, we performed ferritin testing on male plateletpheresis donors with hemoglobin levels less than 13.5 g/dL. Multivariable logistic regression identified risk factors for low ferritin (LF; ferritin ≤26 ng/mL) and absent iron stores (AIS; ferritin <12 ng/mL). To assess the impact of notifying donors of LF results, we compared donation behavior of "Test" subjects before and after sending an LF notification letter to that of "Control" subjects before and after increasing the minimum hemoglobin for male donors. An electronic survey to Test donors inquired about iron supplementation practices. RESULTS: Prevalence of LF was 50% and AIS was 23%, with increase in risk associated with more frequent SDP donation, both controlling for RBC donation and in donors with no recent RBC donations. Donation frequency after intervention declined less in 1272 Test donors (19%, from 13.9 to 11.2 annualized donations) than in 878 Control donors (49%, from 12.3 to 6.3 donations). Only 20% of Test donors reported taking supplemental iron when they received the LF letter; 64% of those not taking iron initiated iron supplementation following the letter. CONCLUSIONS: Donors were responsive to notification of LF and attendant messaging on iron supplementation. Ferritin testing potentially benefits donor health and a stable platelet supply.

The impact of Babesia microti blood donation screening.

BACKGROUND: Babesia microti, an intraerythrocytic parasite endemic in the Northeast and upper Midwest United States, is responsible for over 200 reported cases of transfusion-transmitted babesiosis (TTB). The American Red Cross has prospectively screened donations in endemic areas for B. microti since 2012. METHODS: Blood donation samples from Massachusetts, Connecticut, Minnesota, and Wisconsin were tested by arrayed fluorescence immunoassay and real-time polymerase chain reaction. Donors with reactive results by any test were deferred and invited to participate in a follow-up study. RESULTS: Screening of 506,540 donations (June 2012-May 2018) yielded 1299 reactives, 177 of which were DNA and antibody positive and 25 DNA positive only. During the same time, 23 unscreened RBC units collected in Connecticut and Massachusetts were involved in TTB cases, making the risk of transmitting the infection from an unscreened donation in these two states 15.6-times greater than from a Babesia-negative unit. B. microti screening in Connecticut and Massachusetts has been associated with a reduction in TTB cases; none reported from blood donors residing in Connecticut since 2016. The positive donor rate has also decreased in Connecticut from 0.67% in 2013 to 0.23% in 2017. Ongoing follow-up testing has shown that only 10% of antibody-positive donors serorevert within 1 year, while 94% of polymerase chain reacton-positive donors become negative within 12 months. CONCLUSIONS: Blood donation screening for B. microti in endemic areas effectively mitigates TTB risk. Screening should be considered for all areas demonstrating ongoing risk defined as clinical cases or positive blood donors including those associated with TTB cases.

Cognitive Behavioral Therapy in the Treatment of Insomnia.

Insomnia disorder is present in as much as 30% of the general adult population. Given the significant adverse effects of pharmacotherapy, cognitive behavioral therapy (CBT) has been found to be an effective alternative in individuals with insomnia. CBT for insomnia (CBTi) encompasses sleep hygiene, stimulus control, sleep restriction, cognitive therapy, and relaxation training. In this article we review evidence that establishes CBTi as a useful treatment affecting remission, sleep onset latency, wakefulness after sleep, sleep efficiency, and sleep quality in adults with insomnia to include older adults and adolescents. In addition, we briefly highlight various CBTi delivery methods as well as barriers to accessing this safe and effective therapy.

Evaluation of neck masses in adults.

Neck masses are often seen in clinical practice, and the family physician should be able to determine the etiology of a mass using organized, efficient diagnostic methods. The first goal is to determine if the mass is malignant or benign; malignancies are more common in adult smokers older than 40 years. Etiologies can be grouped according to whether the onset/duration is acute (e.g., infectious), subacute (e.g., squamous cell carcinoma), or chronic (e.g., thyroid), and further narrowed by patient demographics. If the history and physical examination do not find an obvious cause, imaging and surgical tools are helpful. Contrast-enhanced computed tomography is the initial diagnostic test of choice in adults. Computed tomography angiography is recommended over magnetic resonance angiography for the evaluation of pulsatile neck masses. If imaging rules out involvement of underlying vital structures, a fine-needle aspiration biopsy can be performed, providing diagnostic information via cytology, Gram stain, and bacterial and acid-fast bacilli cultures. The sensitivity and specificity of fine-needle aspiration biopsy in detecting a malignancy range from 77% to 97% and 93% to 100%, respectively.

Long-Term Symptoms Associated With SARS-CoV-2 Infection Among Blood Donors.

Importance: Long-term symptoms, lasting more than 4 consecutive weeks after acute COVID-19 disease, are an important consequence of SARS-CoV-2 infection. Many prior studies have lacked a non-SARS-CoV-2-infected control population to distinguish background prevalence of symptoms from the direct impact of COVID-19 disease. Objective: To examine the prevalence of long-term physical and mental health symptoms associated with SARS-CoV-2 infection in a large population of blood donors based on self-report and serologic test results. Design, Setting, and Participants: This cross-sectional study included American Red Cross blood donors (aged ≥18 years) who were surveyed between February 22 and April 21, 2022, about new long-term symptoms arising after March 2020 and their SARS-CoV-2 infection status. All participants underwent at least 1 serologic test for antinucleocapsid antibodies between June 15, 2020, and December 31, 2021. Exposures: SARS-CoV-2 infection as defined by a self-reported, confirmed acute infection or antinucleocapsid antibody positivity. Main Outcomes and Measures: New long-term symptoms since March 2020, including 5 symptom categories (neurologic, gastrointestinal, respiratory and cardiac, mental health, and other). Results: Among 818 361 individuals who received the survey, 272 965 (33.4%) responded, with 238 828 meeting the inclusion criteria (138 576 [58.0%] female; median [IQR] age, 59.0 [47.0-67.0] years). Of the 83 015 individuals with a history of SARS-CoV-2 infection, 43.3% reported new long-term symptoms compared with 22.1% of those without a history of SARS-CoV-2 infection. After controlling for age, sex, race and ethnicity, and number of underlying conditions, those with a history of SARS-CoV-2 infection had an increased odds of new long-term symptoms compared with those without (adjusted odds ratio [AOR], 2.55; 95% CI, 2.51-2.61). Female sex and a history of chronic conditions were associated with new long-term symptoms. Long-term symptoms in the other category (AOR, 4.14; 95% CI, 4.03-4.25), which included changes in taste or smell, and the respiratory and cardiac symptom categories (AOR, 3.21; 95% CI, 3.12-3.31) were most associated with prior SARS-CoV-2 infection. Mental health long-term symptoms were also associated with prior SARS-CoV-2 infection (AOR, 1.05; 95%, CI, 1.02-1.08). Conclusions and Relevance: This study's findings suggest that long-term symptoms lasting more than 4 weeks are common in the adult population, but there is a significantly higher prevalence among those with SARS-CoV-2 infection. Continued efforts to define and track long-term sequelae of SARS-CoV-2 using a control group without infection and serologic information to include those who had asymptomatic or unidentified infections are needed.

A Longitudinal Study of Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Response in a Subset of United States Blood Donors.

Background: Blood donors were tested for antibodies to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2); resulting antibody levels were monitored over time. Methods: Donors reactive to anti-SARS-CoV-2 spike protein (S1-total antibodies) participated in a follow-up study of 18 months. Testing for nucleocapsid antibodies distinguished between vaccination and infection. Vaccination and symptom information were collected for anti-S1-reactive donors by completing a survey. Results: The majority of 249 followed donors were over 60 years old (54%), White (90%), and female (58%); 83% had not been vaccinated at enrollment, but by study completion, only 29% remained nonvaccinated. Of the 210 (84%) anti-N-reactive donors, 138 (66%) reported vaccination, whereas 37 (95%) of donors vaccinated and anti-N negative at enrollment remained uninfected. Vaccinated (2 doses) and infected donors showed a steady increase in anti-S1 that increased markedly for vaccinated donors after a booster and infected donors after vaccination (slightly higher for those with hybrid immunity), whereas anti-N levels declined. Most surveyed nonvaccinated donors (65%) reported symptoms, whereas 85% of vaccinated donors were asymptomatic. A coronavirus disease 2019 (COVID-19) diagnosis was reported by 48 (31%) nonvaccinated and 3 (8%) vaccinated donors. Of asymptomatic donors, 38% never tested diagnostically for COVID-19, and 35% tested negative, suggesting an absence of knowledge of the infection. Conclusions: Healthy blood donors were vaccinated at high rates and remained mostly asymptomatic and noninfected, whereas approximately two thirds of infected donors reported symptoms. Anti-S1 levels increased while anti-N decreased over 18 months but remained comparable between vaccinated and hybrid immune individuals with dramatic anti-S1 increases after vaccination or boosting.

Influence of Dietary Nitrate Supplementation on Physical Performance and Body Composition Following Offseason Training in Division I Athletes.

Purpose: To determine the effects of dietary nitrate supplementation, in the form of red spinach extract (RSE), on adaptations to offseason training in collegiate athletes.Methods: Sixteen Division I male baseball athletes (20.5 ± 1.7y, 90.4 ± 0.5 kg) enrolled in this study and were randomized into a RSE (n = 8) or placebo (n = 8; PL) group. Athletes completed an 11-week resistance training program during the offseason, which consisted of 2-3 workouts per week of upper and lower-body exercises and baseball-specific training. Athletes consumed a RSE (2 g; 180 mg nitrate) or PL supplement daily for the entire offseason training program. Pre and post-training, all athletes underwent one-repetition maximum (1RM) strength testing for the bench press and completed a Wingate anaerobic cycle test (WAnT). Body composition analysis was completed via a 4-compartment model, as well as muscle thickness (MT) measurement of the rectus femoris (RF) and vastus lateralis (VL) via ultrasonography. Resting heart rate and blood pressure (BP) were also obtained. Separate repeated measures analyses of variance were used to analyze all data.Results: Significant (p ≤ 0.05) main effects for time were observed for improved bench 1RM, fat-free mass, body fat percentage, RF MT, and VL MT. No significant group x time interactions (p > 0.05) were found for any measure of performance, body composition, or cardiovascular health. However, a trend for improved peak power in the WAnT was observed (p = 0.095; η2=0.200).Conclusions: These data suggest that daily RSE supplementation had no effect on performance, body composition, or cardiovascular measures in male Division I baseball players following offseason training.