IMPORTANCE An estimated 1% to 3% of children with SARS-CoV-2 infection will develop post- COVID-19 condition (PCC). OBJECTIVE To evaluate the odds of PCC among children with COVID-19 vaccination prior to SARSCoV-2 infection compared with odds among unvaccinated children. DESIGN, SETTING, AND PARTICIPANTS In this case-control study, children were enrolled in a multisite longitudinal pediatric cohort from July 27, 2021, to September 1, 2022, and followed up through May 2023. Analysis used a case (PCC reported)-control (no PCC reported) design and included children aged 5 to 17 years whose first real time-polymerase chain reaction (RT-PCR)- confirmed SARS-CoV-2 infection occurred during the study period, who were COVID-19 vaccine age-eligible at the time of infection, and who completed a PCC survey at least 60 days after infection. From December 1, 2022, to May 31, 2023, children had weekly SARS-CoV-2 testing and were surveyed regarding PCC (>= 1 new or ongoing symptom lasting >= 1 month after infection). EXPOSURES COVID-19 mRNA vaccination status at time of infection was the exposure of interest; participants were categorized as vaccinated (>= 2-dose series completed >= 14 days before infection) or unvaccinated. Vaccination status was verified through vaccination cards or vaccine registry and/or medical records when available. MAIN OUTCOME AND MEASURES Main outcomes were estimates of the odds of PCC symptoms. Multivariate logistic regression was performed to estimate the odds of PCC among vaccinated children compared with odds of PCC among unvaccinated children. RESULTS A total of 622 participants were included, with 28 (5%) case participants and 594(95%) control participants. Median (IQR) age was 10.0 (7.0-11.9) years for case participants and 10.3 (7.8-12.7) years for control participants (P = .37). Approximately half of both groups reported female sex (13 case participants [46%] and 287 control participants [48%]). Overall, 57% of case participants (16 children) and 77% of control participants (458 children) were vaccinated (P = .05). After adjusting for demographic characteristics, number of acute COVID-19 symptoms, and baseline health, COVID-19 vaccination was associated with decreased odds of 1 or more PCC symptom (adjusted odds ratio [aOR], 0.43; 95% CI, 0.19-0.98) and 2 or more PCC symptoms (aOR, 0.27; 95% CI, 0.10-0.69). CONCLUSIONS AND RELEVANCE In this study, mRNA COVID-19 vaccination was associated with reduced odds of PCC in children. The aORs correspond to an estimated 57% and 73% reduced likelihood of 1 or more and 2 or more PCC symptoms, respectively, among vaccinated vs unvaccinated children. These findings suggest benefits of COVID-19 vaccination beyond those associated with protection against acute COVID-19 and may encourage increased pediatric uptake.

Background/Objectives: We aimed to assess the impact of updates in the 2024 AMA Guides to the Evaluation of Permanent Impairment, Sixth Edition, on spine and pelvis impairment ratings compared to the 2008 Sixth Edition and to investigate potential correlations with legislative, judicial, and economic factors. Methods: Nineteen clinical vignettes focused on spine and pelvis conditions were analyzed by two expert evaluators, comparing the impairment ratings derived from both editions. Results: Following the spine and pelvis impairment rating procedures from each edition, the 2024 impairment values showed a high correlation and statistical equivalence to those derived from the 2008 methods. Conclusions: The AMA Guides Sixth Edition 2024 update for spine and pelvis impairments offers enhanced diagnosis-based impairment tables and more transparent processes, improving efficiency while preserving the accuracy, validity, and reliability of previous editions.

OBJECTIVE:Cannabis use is expanding rapidly, and a guideline is needed to address workplace issues. METHODS:The ACOEM Guidelines methodology was used to develop an evidence-based guideline. RESULTS:There is some evidence suggesting potential efficacy of cannabis for treatment of spasticity associated with multiple sclerosis. There is no quality evidence of efficacy for treatment of common and typical work-related disorders such as back pain, chronic radiculopathy, neuropathic pain, and other acute or chronic pain disorders. Quality evidence supports lack of efficacy for postoperative pain. There are many adverse effects, including cancers, cardiovascular diseases, psychotic disorders, and safety risks. There is a rising concern that cannabis may cause schizophrenia. CONCLUSIONS:Cannabis is not recommended for treatment of typical potentially work-related conditions. Cannabis use for any purpose is not recommended for those in safety-sensitive positions.

OBJECTIVE:This abbreviated version of the American College of Occupational and Environmental Medicine's (ACOEM) Work Disability Prevention and Management Guideline reviews the available evidence and provides recommendations to clinicians regarding interventions to help patients remain at or return to work. METHODS:Systematic literature reviews were conducted. Studies were graded and evidence tables were created, with involvement of a multidisciplinary expert panel that evaluated the evidence and finalized recommendations for all clinical questions. Extensive peer review was performed. Consensus recommendations were formulated when evidence was lacking. RESULTS:Evidence-based recommendations have been developed to guide work disability prevention and management. CONCLUSIONS:Clinicians should utilize quality evidence in determining treatment methods to prevent and alleviate work disability for workers. This guideline offers an evidence-based framework for preventing and mitigating work disability for individual adults in the active workforce. It is designed for use by healthcare clinicians who desire to minimize the negative impact of health conditions on working people's lives and livelihoods.

OBJECTIVE:To determine the ease of use, accuracy, consistency, reliability, and reproducibility for rating lower limb conditions when transitioning to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) Sixth Edition 2024 developed using the RAND/UCLA modified Delphi Appropriateness Method compared with the AMA Guides Sixth Edition 2008. METHODS:Three physician experts and four premedical students completed two rounds of impairment ratings using methods from the AMA Guides Sixth Edition 2008 versus the AMA Guides Sixth Edition 2024. Impairment values and completion times for each method were compared across groups. RESULTS:For experts, the average time to complete an impairment rating was 4.1 minutes using the AMA Guides Sixth Edition 2024 compared with 16.7 minutes using the AMA Guides Sixth Edition 2008, maintaining 100% accuracy and reliability for both methods. Premedical students averaged 5.3 minutes with the AMA Guides Sixth Edition 2024 and 24.0 minutes with the AMA Guides Sixth Edition 2008, showing increased accuracy, consistency, reliability, and reproducibility with AMA Guides 2024. CONCLUSION:The AMA Guides Sixth Edition 2024 represents a notable advancement in impairment evaluation, offering a more efficient, accurate, and reliable system for lower limb impairment assessments. This update not only benefits healthcare providers and patients but also sets a new standard in occupational health by preserving the accuracy, consistency, reliability, and reproducibility of impairment ratings while streamlining the evaluation process.

Background/Objectives: This study aims to assess the ease of use, accuracy, consistency, reliability, and reproducibility in evaluating spine and pelvis conditions when transitioning from the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) Sixth Edition 2008 to the newly updated Sixth Edition 2024. Methods: Two rounds of impairment ratings were performed by a team consisting of three physician experts and four premedical students, focusing on a comparison between the 2008 and 2024 editions of the AMA Guides. The analysis included both the impairment values generated and the time taken to complete assessments with each version. Results: For the expert group, the mean duration required to complete an impairment rating was 5.0 min with the AMA Guides 2024, compared to 15.4 min using the AMA Guides 2008, with both editions achieving 100% accuracy and reliability. The premedical students demonstrated similar improvements, averaging 8.4 min per rating with the 2024 edition versus 26.4 min with the 2008 edition. The AMA Guides 2024 yielded enhanced accuracy, consistency, reliability, and reproducibility. Conclusions: The AMA Guides Sixth Edition 2024 represents a significant advancement in impairment evaluation, particularly for spine and pelvis assessments. This updated edition introduces a more streamlined and time-efficient process while preserving the accuracy, consistency, and reproducibility essential to high-quality impairment ratings. By enhancing clarity and standardization, it sets a new standard in occupational health, offering a reliable framework that supports both clinical assessment and administrative oversight.

Background/Objectives: This study examines the effect of the 2024 update to the AMA Guides to the Evaluation of Permanent Impairment, Sixth Edition, on lower limb impairment determinations in comparison to the 2008 edition. It also explores the broader influence of these changes on regulatory, economic, and adjudicative considerations relevant to physician application and interpretation. Methods: Two experienced evaluators independently reviewed 23 standardized lower limb case scenarios, applying both the 2008 and 2024 methodologies. Each assessment was based solely on clinical history, physical examination findings, and diagnostic test results. Impairment values were then calculated and analyzed for consistency across editions. Results: The 2024 lower limb impairment framework produced outcomes that closely mirrored those of the 2008 edition, with intraclass correlation coefficients of 0.9962 for the lower limb and 0.9951 for whole-person impairment, underscoring the strong consistency between editions. Conclusions: The revised 2024 edition for lower limb assessment enhances procedural clarity and integrates improved diagnosis-based impairment tools without disrupting prior impairment values. These refinements are intended to improve utility for clinical and nonclinical stakeholders, ensuring reliable evaluations while minimizing systemic disruption.

To understand how coronavirus disease 2019 vaccines impact infection risk in children <5 years, we assessed risk of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection from September 2022 to April 2023 in 3 cohort studies. There was no difference in risk by vaccination status. While vaccines reduce severe disease, they may not reduce SARS-CoV-2 infections in naïve young children.

Introduction Firefighters face frequent physical and psychosocial stressors, increasing their risk for hypertension. Rising call volumes with a stable workforce have heightened occupational burdens. To meet their occupational demands while increasing time off-duty, fire departments across the country have switched from a 24 hours on 48 hours off (termed ‘24/48’) work schedule to one that increases the number of consecutive days off (eg, 1 day on, 3 days off, 2 days on, 3 days off (termed ‘1/3/2/3’) or 48 hours on 96 hours off (termed ‘48/96’)). However, these schedule changes come at the expense of increasing time on-duty, which may have negative health and safety consequences. This paper provides the framework and methods to investigate how these schedules (24/48, 1/3/2/3 and 48/96) impact hypertension risk, well-being and safety among firefighters.Methods and analysis This quasi-experimental study assesses hypertension risk (primary outcome) markers, including 48-hour ambulatory blood pressure and safety (secondary outcome) using the psychomotor vigilance test and incidence of injuries. The study encompasses a cross-sectional analysis that examines three distinct schedules (24/48, 1/3/2/3 and 48/96) and a prospective analysis, capitalising on a pre-planned schedule transition from a 24/48 to a 1/3/2/3, as a natural experiment without any intervention from the study team. Additionally, the mediating role of sleep (assessed objectively using actigraphy and subjectively using questionnaires) and daily stress in the relationship between work schedule and hypertension risk or sustained attention is investigated to inform both mechanisms and general considerations for developing and promoting a healthy work design for firefighters. The feasibility and acceptability of the three schedules are assessed using validated surveys and qualitative interviews.Ethics and dissemination The study received approval from the institutional review boards of Oregon Health & Science University (IRB# 20553) and the University of Utah (IRB#165866) and engages fire departments in the Pacific Northwest and Utah. It leverages community engagement with these fire departments, offering an exceptional opportunity to examine the physical and mental impacts of firefighters’ work schedules. Aggregate findings will be disseminated through practical resources, benefiting both regional and national firefighting communities.

Objective Describe and evaluate methodological improvements in AMA Guides to the Evaluation of Permanent Impairment (Guides) Sixth Edition 2024, including an updated sequential method and enhanced diagnosis-based impairment tables, compared to the Guides Sixth 2008. Methods Three physician experts and 3 premedical students, respectively, completed 2 rounds of impairment ratings using the AMA Guides Sixth 2008 versus 2024 methods. Impairment values and completion times using each method were compared for both groups. Results Time to complete an impairment rating by experts averaged 3.5 minutes using Guides 2024 compared with 13.9 minutes using Guides 2008, with 100% accuracy and reliability for both. Students' time averaged 5.3 and 15.9 minutes, respectively, with increased accuracy and reliability with Guides 2024. Conclusions The Guides Sixth 2024 allowed more efficient impairment ratings while retaining accuracy, consistency, reliability, and reproducibility.

The extent to which semi-quantitative antibody levels confer protection against SARS-CoV-2 infection in populations with heterogenous immune histories is unclear. Two nested case-control studies were designed within the multisite HEROES/RECOVER prospective cohort of frontline workers to study the relationship between antibody levels and protection against first-time post-vaccination infection and reinfection with SARS-CoV-2 from December 2021 to January 2023. All participants submitted weekly nasal swabs for rRT-PCR testing and blood samples quarterly and following infection or vaccination. Cases of first-time post-vaccination infection following a third dose of monovalent (origin strain WA-1) mRNA vaccine (n = 613) and reinfection (n = 350) were 1:1 matched to controls based on timing of blood draw and other potential confounders. Conditional logistic regression models were fit to estimate infection risk reductions associated with 3-fold increases in end titers for receptor binding domain (RBD). In first-time post-vaccination and reinfection study samples, most were female (67%, 57%), non-Hispanic (82%, 68%), and without chronic conditions (65%, 65%). The odds of first-time post-vaccination infection were reduced by 21% (aOR = 0.79, 95% CI = [0.66-0.96]) for each 3-fold increase in RBD end titers. The odds of reinfection associated with a 3-fold increase in RBD end titers were reduced by 23% (aOR = 0.77, 95% CI = [0.65-0.92] for unvaccinated individuals and 58% (aOR = 0.42, 95% CI = [0.22-0.84]) for individuals with three mRNA vaccine doses following their first infection. Frontline workers with higher antibody levels following a third dose of mRNA COVID-19 vaccine were at reduced risk of SARS-CoV-2 during Omicron predominance. Among those with previous infections, the point estimates of risk reduction associated with antibody levels was greater for those with three vaccine doses compared to those who were unvaccinated.

Background:Immunogenicity studies suggest that recombinant influenza vaccine (RIV) may provide better protection against influenza than standard-dose inactivated influenza vaccines (SD IIV). This randomized trial evaluated the relative vaccine effectiveness (VE) and immunogenicity of RIV versus SD IIV in frontline workers and students aged 18-64 years. Methods:Participants were randomized to receive RIV or SD IIV and followed for reverse-transcription polymerase chain reaction (RT-PCR)-confirmed influenza during the 2022-2023 influenza season. Sera were collected from a subset of participants before and at 1 and 6 months postvaccination and tested by hemagglutination inhibition for A/H1N1, A/H3N2, B/Yamagata, and B/Victoria and against cell-grown vaccine reference viruses for A/H1N1 and A/H3N2. Results:Overall, 3988 participants were enrolled and vaccinated (25% of the trial sample size goal); RT-PCR-confirmed influenza occurred in 20 of 1963 RIV recipients and 28 of 1964 SD IIV recipients. Relative VE was 29% (95% confidence interval [CI], -26% to 60%). In the immunogenicity substudy (n = 118), the geometric mean titer ratio (GMTR) comparing RIV to SD IIV at 1 month was 2.3 (95% CI, 1.4-3.7) for cell-grown A/H1N1, 2.1 (95% CI, 1.3-3.4) for cell-grown A/H3N2, 1.1 (95% CI, .7-1.6) for B/Victoria, and 1.4 (95% CI, .9-2.0) for B/Yamagata. At 6 months, GMTRs were >1 against A/H1N1, A/H3N2, and B/Yamagata. Conclusions:Relative VE of RIV compared to SD IIV did not reach statistical significance, but RIV elicited more robust humoral immune responses to 2 of 4 vaccine viruses at 1 month and 3 of 4 viruses at 6 months after vaccination, suggesting possible improved and sustained immune protection from RIV. Clinical Trials Registration. NCT05514002.

Importance Bivalent mRNA COVID-19 vaccines were recommended in the US for children and adolescents aged 12 years or older on September 1, 2022, and for children aged 5 to 11 years on October 12, 2022; however, data demonstrating the effectiveness of bivalent COVID-19 vaccines are limited. Objective To assess the effectiveness of bivalent COVID-19 vaccines against SARS-CoV-2 infection and symptomatic COVID-19 among children and adolescents. Design, Setting, and Participants Data for the period September 4, 2022, to January 31, 2023, were combined from 3 prospective US cohort studies (6 sites total) and used to estimate COVID-19 vaccine effectiveness among children and adolescents aged 5 to 17 years. A total of 2959 participants completed periodic surveys (demographics, household characteristics, chronic medical conditions, and COVID-19 symptoms) and submitted weekly self-collected nasal swabs (irrespective of symptoms); participants submitted additional nasal swabs at the onset of any symptoms. Exposure Vaccination status was captured from the periodic surveys and supplemented with data from state immunization information systems and electronic medical records. Main Outcome and Measures Respiratory swabs were tested for the presence of the SARS-CoV-2 virus using reverse transcriptase-polymerase chain reaction. SARS-CoV-2 infection was defined as a positive test regardless of symptoms. Symptomatic COVID-19 was defined as a positive test and 2 or more COVID-19 symptoms within 7 days of specimen collection. Cox proportional hazards models were used to estimate hazard ratios for SARS-CoV-2 infection and symptomatic COVID-19 among participants who received a bivalent COVID-19 vaccine dose vs participants who received no vaccine or monovalent vaccine doses only. Models were adjusted for age, sex, race, ethnicity, underlying health conditions, prior SARS-CoV-2 infection status, geographic site, proportion of circulating variants by site, and local virus prevalence. Results Of the 2959 participants (47.8% were female; median age, 10.6 years [IQR, 8.0-13.2 years]; 64.6% were non-Hispanic White) included in this analysis, 25.4% received a bivalent COVID-19 vaccine dose. During the study period, 426 participants (14.4%) had laboratory-confirmed SARS-CoV-2 infection. Among these 426 participants, 184 (43.2%) had symptomatic COVID-19, 383 (89.9%) were not vaccinated or had received only monovalent COVID-19 vaccine doses (1.38 SARS-CoV-2 infections per 1000 person-days), and 43 (10.1%) had received a bivalent COVID-19 vaccine dose (0.84 SARS-CoV-2 infections per 1000 person-days). Bivalent vaccine effectiveness against SARS-CoV-2 infection was 54.0% (95% CI, 36.6%-69.1%) and vaccine effectiveness against symptomatic COVID-19 was 49.4% (95% CI, 22.2%-70.7%). The median observation time after vaccination was 276 days (IQR, 142-350 days) for participants who received only monovalent COVID-19 vaccine doses vs 50 days (IQR, 27-74 days) for those who received a bivalent COVID-19 vaccine dose. Conclusion and Relevance The bivalent COVID-19 vaccines protected children and adolescents against SARS-CoV-2 infection and symptomatic COVID-19. These data demonstrate the benefit of COVID-19 vaccine in children and adolescents. All eligible children and adolescents should remain up to date with recommended COVID-19 vaccinations.

Objectives The aims of the study are to evaluate how upper limb impairment ratings are affected by updates to the AMA Guides to the Evaluation of Permanent Impairment (AMA Guides) Sixth Edition 2024 compared with the AMA Guides Sixth Edition 2008 and to investigate potential correlations with judicial, legislative, and economic factors. Methods Two expert evaluators reviewed 31 upper limb clinical vignettes from the 2008 and 2024 versions. The impairment ratings for each version were compared. Results After following the impairment ratings steps in each version, the results for 2024 showed no significant differences when compared with the impairment ratings generated using 2008 methods (Cohen’s kappa = 1.00). Conclusions The updated AMA Guides Sixth Edition 2024 with improved, transparent processes and enhanced diagnosis-based impairment tables provides efficiency while retaining the accuracy, validity, and reliability of past versions of the AMA Guides.

Abstract Introduction The pathophysiological bases of musculoskeletal disorders (MSDs) is/are uncertain, resulting in reduced opportunities for prevention. Methods Nine-year prospective cohort data from 1,224 workers in 3 US states were analyzed. IRBs approved of the protocol. Baseline data included questionnaires, structured interviews, physical examinations, anthropometric measurements, and nerve conduction studies. Job physical factors were individually measured. Monthly follow-ups were conducted. Framingham risk scores were calculated. A priori case definitions were constructed for carpal tunnel syndrome, lateral/medial epicondylopathy, and rotator cuff tendinopathy. Data were also analyzed from a second 8-year prospective cohort of 828 workers for low back pain (LBP) using similar methods. Results Adjusted RRs (including job physical factors) for one or more MSDs increased to 3.90 (95% CI, 2.20, 6.90) among those with 10-year CVD risk scores above 15% and 17.4 (95% CI 3.85, 78.62) among those with 4+ disorders. By contrast with these common upper extremity MSDs, cardiovascular risks did not confer an increased risk for LBP. Discussion Cardiovascular risk factors are strong risk factors for common upper extremity MSDs. The relationships become stronger among those with increasing numbers of MSDs. Data suggest potential microvascular pathophysiology. The magnitude of risks is sufficiently high that confounding appears improbable. These data also suggest if there is a microvascular cause, it does not involve LBP. LBP continues to stand in search of explanatory pathophysiology. Conclusion While job physical factors remain as important modifiable risks, CVD factors are strongly associated with the development of common MSDs, but not LBP. Risks among those with multiple MSDs are considerably stronger.

Background: To determine the impacts of statewide coronavirus disease 2019 (COVID-19)-related public health and social measures (PHSMs) and attempted pandemic mitigation measures on years of potential life lost (YPLL). Methods: The “openness score” of each state during the COVID-19 pandemic was obtained using two open-source sites, the Multistate openness score and the Wallethub openness score. These scores combined various PHSMs, such as restrictions on gatherings and closing various types of businesses. Using data from the Centers for Disease Control and Prevention (CDC) Wonder database, the differences in prepandemic (2017-2019) and pandemic excess mortality were calculated in terms of YPLL and then compared to the openness scores using univariate regression modeling. Results: States that instituted more restrictive PHSMs as measured by openness scores failed to experience reductions in YPLL. On the contrary, there were trends toward statistical significance associating greater YPLL with the institution of more stringent PHSMs (p = 0.109 and p = 0.080 for Multistate and Wallethub, respectively). Discussion: This study suggests restrictive PHSMs were ineffective for improving mortality in this pandemic and trended toward increasing mortality in the younger population, presumably from other, non-COVID-19 causes.

Background. Data are limited on whether vaccination reduces post COVID conditions (PCCs) risk after less severe nonhospitalized coronavirus disease 2019 (COVID-19). This study assessed whether COVID-19 vaccination protected against PCCs in persons with mild initial infections during Delta and Omicron variant predominance. Methods. This study utilized a case-control design, nested within the HEROES-RECOVER cohort. Participants aged >= 18 years with test-confirmed severe acute respiratory syndrome coronavirus disease 2 (SARS-CoV-2) between 28 June 2021 and 14 September 2022 were surveyed for PCCs, defined by symptoms lasting >4 weeks after initial infection. Cases self-reported PCCs and controls self-reported no PCCs. The exposure was messenger RNA (mRNA) COVID-19 vaccination (2 or 3 monovalent doses). Odds of PCCs among vaccinated and unvaccinated persons were compared with logistic regression. Results. Of 936 participants, 23.6% reported PCCs and 83.2% were vaccinated. Participants who received 3 vaccine doses had lower odds of PCC-related gastrointestinal, neurological, and other symptoms compared to unvaccinated participants (adjusted odds ratio [95% confidence interval]: 0.37 [.16-.85], 0.56 [.32-.97], and 0.48 [.25-.91], respectively). Conclusions. COVID-19 vaccination protected against development of PCCs among persons with mild infection during both Delta and Omicron variant predominance, supporting vaccination as an important PCCs prevention tool.

Objectives: Pediatric COVID-19 vaccine hesitancy and uptake is not well understood. Among parents of a prospective cohort of children aged 6 months-17 years, we assessed COVID-19 vaccine knowledge, attitudes, and practices (KAP), and uptake over 15 months. Methods: The PROTECT study collected sociodemographic characteristics of children at enrollment and COVID19 vaccination data and parental KAPs quarterly. Univariable and multivariable logistic regression models were used to test the effect of KAPs on vaccine uptake; McNemar's test for paired samples was used to evaluate KAP change over time. Results: A total of 2,837 children were enrolled, with more than half (61 %) vaccinated by October 2022. Positive parental beliefs about vaccine safety and effectiveness strongly predicted vaccine uptake among children aged 5-11 years (aOR 13.1, 95 % CI 8.5-20.4 and aOR 6.4, 95 % CI 4.3-9.6, respectively) and children aged 12+ years (aOR 7.0, 95 % CI 3.8-13.0 and aOR 8.9, 95 % CI 4.4-18.0). Compared to enrollment, at follow-up parents (of vaccinated and unvaccinated children) reported higher self -assessed vaccine knowledge, but more negative beliefs towards vaccine safety, effectiveness, and trust in government. Parents unlikely to vaccinate their children at enrollment reported more positive beliefs on vaccine knowledge, safety, and effectiveness at follow-up. Conclusion: The PROTECT cohort allows for an examination of factors driving vaccine uptake and how beliefs about COVID-19 and the COVID-19 vaccines change over time. Findings of the current analysis suggest that these beliefs change over time and policies aiming to increase vaccine uptake should focus on vaccine safety and effectiveness.

Hybrid immunity, as a result of infection and vaccination to SARS-CoV-2, has been well studied in adults but limited evidence is available in children. We evaluated the antibody responses to primary SARS-CoV-2 infection among vaccinated and unvaccinated children aged ≥ 5 years. Methods: A longitudinal cohort study of children aged ≥ 5 was conducted during August 2021–August 2022, at sites in Arizona, Texas, Utah, and Florida. Children submitted weekly nasal swabs for PCR testing and provided sera 14–59 days after PCR-confirmed SARS-CoV-2 infection. Antibodies were measured by ELISA against the receptor-binding domain (RBD) and S2 domain of ancestral Spike (WA1), in addition to Omicron (BA.2) RBD, following infection in children, with and without prior monovalent ancestral mRNA COVID-19 vaccination. Results: Among the 257 participants aged 5 to 18 years, 166 (65%) had received at least two mRNA COVID-19 vaccine doses ≥ 14 days prior to infection. Of these, 53 occurred during Delta predominance, with 37 (70%) unvaccinated at the time of infection. The remaining 204 infections occurred during Omicron predominance, with 53 (26%) participants unvaccinated. After adjusting for weight, age, symptomatic infection, and gender, significantly higher mean RBD AUC values were observed among the vaccinated group compared to the unvaccinated group for both WA1 and Omicron (p < 0.0001). A smaller percentage of vaccinated children reported fever during illness, with 55 (33%) reporting fever compared to 44 (48%) unvaccinated children reporting fever (p = 0.021). Conclusions: Children with vaccine-induced immunity at the time of SARS-CoV-2 infection had higher antibody levels during convalescence and experienced less fever compared to unvaccinated children during infection.