The Infectious Diseases Society of America Guidelines on the Diagnosis of COVID-19: Molecular Diagnostic Testing (December 2023).

Accurate molecular diagnostic tests are necessary for confirming a diagnosis of coronavirus disease 2019 (COVID-19) and for identifying asymptomatic carriage of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The number of available SARS-CoV-2 nucleic acid detection tests continues to increase as does the COVID-19 diagnostic literature. Thus, the Infectious Diseases Society of America (IDSA) developed an evidence-based diagnostic guideline to assist clinicians, clinical laboratorians, patients, and policymakers in decisions related to the optimal use of SARS-CoV-2 nucleic acid amplification tests. In addition, we provide a conceptual framework for understanding molecular diagnostic test performance, discuss nuances of test result interpretation in a variety of practice settings, and highlight important unmet research needs related to COVID-19 diagnostic testing. IDSA convened a multidisciplinary panel of infectious diseases clinicians, clinical microbiologists, and experts in systematic literature review to identify and prioritize clinical questions and outcomes related to the use of SARS-CoV-2 molecular diagnostics. Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make testing recommendations. The panel agreed on 12 diagnostic recommendations. Access to accurate SARS-CoV-2 nucleic acid testing is critical for patient care, hospital infection prevention, and the public health response to COVID-19 infection. Information on the clinical performance of available tests continues to grow, but the quality of evidence of the current literature to support this updated molecular diagnostic guideline remains moderate to very low. Recognizing these limitations, the IDSA panel weighed available diagnostic evidence and recommends nucleic acid testing for all symptomatic individuals suspected of having COVID-19. In addition, testing is suggested for asymptomatic individuals with known or suspected contact with a COVID-19 case when the results will impact isolation/quarantine/personal protective equipment (PPE) usage decisions. Evidence in support of rapid testing and testing of upper respiratory specimens other than nasopharyngeal swabs, which offer logistical advantages, is sufficient to warrant conditional recommendations in favor of these approaches.

Infectious Diseases Society of America Guidelines on the Diagnosis of COVID-19: Serologic Testing.

BACKGROUND: The role of serologic testing for SARS-CoV-2 has evolved during the pandemic as seroprevalence in global populations has increased. The Infectious Diseases Society of America (IDSA) convened an expert panel to perform a systematic review of the coronavirus disease 2019 (COVID-19) serology literature and construct updated best practice guidance related to SARS-CoV-2 serologic testing. This guideline is an update to the fourth in a series of rapid, frequently updated COVID-19 guidelines developed by IDSA. OBJECTIVE: To develop evidence-based recommendations and identify unmet research needs pertaining to the use of anti-SARS-CoV-2 antibody tests for diagnosis, decisions related to vaccination and administration of monoclonal antibodies or convalescent plasma in immunocompromised patients, and identification of a serologic correlate of immunity. METHODS: A multidisciplinary panel of infectious diseases clinicians, clinical microbiologists and experts in systematic literature reviewed, identified, and prioritized clinical questions related to the use of SARS-CoV-2 serologic tests. Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make testing recommendations. RESULTS: The panel recommends against serologic testing to diagnose SARS-CoV-2 infection in the first two weeks after symptom onset (strong recommendations, low certainty of evidence). Serologic testing should not be used to provide evidence of COVID-19 in symptomatic patients with a high clinical suspicion and repeatedly negative nucleic acid amplification test results (strong recommendation, very low certainty of evidence). Serologic testing may assist with the diagnosis of multisystem inflammatory syndrome in children (strong recommendation, very low certainty of evidence). To seek evidence for prior SARS-CoV-2 infection, the panel suggests testing for IgG, IgG/IgM, or total antibodies to nucleocapsid protein three to five weeks after symptom onset (conditional recommendation, low certainty of evidence). In individuals with previous SARS-CoV-2 infection or vaccination, we suggest against routine serologic testing given no demonstrated benefit to improving patient outcomes (conditional recommendation, very low certainty of evidence.) The panel acknowledges further that a negative spike antibody test may be a useful metric to identify immunocompromised patients who are candidates for immune therapy. CONCLUSIONS: The high seroprevalence of antibodies against SARS-CoV-2 worldwide limits the utility of detecting anti-SARS CoV-2 antibody. The certainty of available evidence supporting the use of serology for diagnosis was graded as very low to low. Future studies should use serologic assays calibrated to a common reference standard.

Seasonality, Clinical Characteristics, and Outcomes of Respiratory Syncytial Virus Disease by Subtype Among Children Aged <5 Years: New Vaccine Surveillance Network, United States, 2016-2020.

BACKGROUND: Respiratory syncytial virus (RSV) is a leading cause of acute respiratory illnesses in children. RSV can be broadly categorized into 2 major subtypes: A and B. RSV subtypes have been known to cocirculate with variability in different regions of the world. Clinical associations with viral subtype have been studied among children with conflicting findings such that no conclusive relationships between RSV subtype and severity have been established. METHODS: During 2016-2020, children aged <5 years were enrolled in prospective surveillance in the emergency department or inpatient settings at 7 US pediatric medical centers. Surveillance data collection included parent/guardian interviews, chart reviews, and collection of midturbinate nasal plus/minus throat swabs for RSV (RSV-A, RSV-B, and untyped) using reverse transcription polymerase chain reaction. RESULTS: Among 6398 RSV-positive children aged <5 years, 3424 (54%) had subtype RSV-A infections, 2602 (41%) had subtype RSV-B infections, and 272 (5%) were not typed, inconclusive, or mixed infections. In both adjusted and unadjusted analyses, RSV-A-positive children were more likely to be hospitalized, as well as when restricted to <1 year. By season, RSV-A and RSV-B cocirculated in varying levels, with 1 subtype dominating proportionally. CONCLUSIONS: Findings indicate that RSV-A and RSV-B may only be marginally clinically distinguishable, but both subtypes are associated with medically attended illness in children aged <5 years. Furthermore, circulation of RSV subtypes varies substantially each year, seasonally and geographically. With introduction of new RSV prevention products, this highlights the importance of continued monitoring of RSV-A and RSV-B subtypes.

The Infectious Diseases Society of America Guidelines on the Diagnosis of COVID-19: Antigen Testing.

BACKGROUND: Immunoassays designed to detect SARS-CoV-2 protein antigens (Ag) are commonly used to diagnose COVID-19. The most widely used tests are lateral flow assays that generate results in approximately 15 minutes for diagnosis at the point-of-care. Higher throughput, laboratory-based SARS-CoV-2 Ag assays have also been developed. The number of commercially available SARS-CoV-2 Ag detection tests has increased rapidly, as has the COVID-19 diagnostic literature. The Infectious Diseases Society of America (IDSA) convened an expert panel to perform a systematic review of the literature and develop best practice guidance related to SARS-CoV-2 Ag testing. This guideline is an update to the third in a series of frequently updated COVID-19 diagnostic guidelines developed by the IDSA. OBJECTIVE: The IDSA's goal was to develop evidence-based recommendations or suggestions that assist clinicians, clinical laboratories, patients, public health authorities, administrators and policymakers in decisions related to the optimal use of SARS-CoV-2 Ag tests in both medical and non-medical settings. METHODS: A multidisciplinary panel of infectious diseases clinicians, clinical microbiologists and experts in systematic literature review identified and prioritized clinical questions related to the use of SARS-CoV-2 Ag tests. A review of relevant, peer-reviewed published literature was conducted through April 1, 2022. Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to assess the certainty of evidence and make testing recommendations. RESULTS: The panel made ten diagnostic recommendations. These recommendations address Ag testing in symptomatic and asymptomatic individuals and assess single versus repeat testing strategies. CONCLUSIONS: U.S. Food and Drug Administration (FDA) SARS-CoV-2 Ag tests with Emergency Use Authorization (EUA) have high specificity and low to moderate sensitivity compared to nucleic acid amplification testing (NAAT). Ag test sensitivity is dependent on the presence or absence of symptoms, and in symptomatic patients, on timing of testing after symptom onset. In contrast, Ag tests have high specificity, and, in most cases, positive Ag results can be acted upon without confirmation. Results of point-of-care testing are comparable to those of laboratory-based testing, and observed or unobserved self-collection of specimens for testing yields similar results. Modeling suggests that repeat Ag testing increases sensitivity compared to testing once, but no empirical data were available to inform this question. Based on these observations, rapid RT-PCR or laboratory-based NAAT remains the testing method of choice for diagnosing SARS-CoV-2 infection. However, when timely molecular testing is not readily available or is logistically infeasible, Ag testing helps identify individuals with SARS-CoV-2 infection. Data were insufficient to make a recommendation about the utility of Ag testing to guide release of patients with COVID-19 from isolation. The overall quality of available evidence supporting use of Ag testing was graded as very low to moderate.

Life-Threatening Complications of Influenza vs Coronavirus Disease 2019 (COVID-19) in US Children.

BACKGROUND: Clinical differences between critical illness from influenza infection vs coronavirus disease 2019 (COVID-19) have not been well characterized in pediatric patients. METHODS: We compared demographics, clinical characteristics, and outcomes of US children (aged 8 months to 17 years) admitted to the intensive care or high-acuity unit with influenza or COVID-19. Using mixed-effects models, we assessed the odds of death or requiring life support for influenza vs COVID-19 after adjustment for age, sex, race and Hispanic origin, and underlying conditions including obesity. RESULTS: Children with influenza (n = 179) were younger than those with COVID-19 (n = 381; median, 5.2 years vs 13.8 years), less likely to be non-Hispanic Black (14.5% vs 27.6%) or Hispanic (24.0% vs 36.2%), and less likely to have ≥1 underlying condition (66.4% vs 78.5%) or be obese (21.4% vs 42.2%), and a shorter hospital stay (median, 5 days vs 7 days). They were similarly likely to require invasive mechanical ventilation (both 30.2%), vasopressor support (19.6% and 19.9%), or extracorporeal membrane oxygenation (2.2% and 2.9%). Four children with influenza (2.2%) and 11 children with COVID-19 (2.9%) died. The odds of death or requiring life support in children with influenza vs COVID-19 were similar (adjusted odds ratio, 1.30; 95% confidence interval, .78-2.15; P = .32). CONCLUSIONS: Despite differences in demographics and clinical characteristics of children with influenza or COVID-19, the frequency of life-threatening complications was similar. Our findings highlight the importance of implementing prevention measures to reduce transmission and disease severity of influenza and COVID-19.

Incidence of and risk factors for influenza-associated hospital encounters in pediatric solid organ transplant recipients.

Few studies have defined the incidence of and risk factors for influenza infection in pediatric solid organ transplant (SOT) recipients. We used a linkage between the Pediatric Health Information System and the Scientific Registry of Transplant Recipients databases to identify posttransplant influenza-associated hospital encounters (IAHEs) in pediatric SOT recipients of single-organ transplants. Among 7997 unique pediatric SOT recipients transplanted between January 01, 2006, and January 06, 2016, estimated 1- and 3-year posttransplant cumulative incidence rates of IAHEs were 2.7% (95% CI, 2.4%-3.1%) and 7.4% (95% CI, 6.8%-8.0%), respectively. One- and 3-year cumulative incidence rates of severe IAHEs were 0.3% (95% CI, 0.2%-0.5%) and 0.9% (95% CI, 0.7%-1.2%), respectively. Multivariable analysis showed that the organ type (adjusted subdistribution hazard ratio [aSHR]-kidney: reference, liver: 0.64 [95% CI, 0.49-0.84], and heart: 0.72 [95% CI, 0.57-0.93]), race/ethnicity (aSHR-non-Hispanic White: reference, non-Hispanic Black: 1.63 [95% CI, 1.29-2.07], Hispanic 1.57 [95% CI, 1.27-1.94]), and increasing age at transplant (aSHR, 0.93 [95% CI, 0.91-0.94]) were significantly associated with IAHE occurrence. Heart transplant recipients had a near statistically significant increase in hazard for severe IAHE (aSHR 1.96 [0.92-3.49]). Our findings may help guide future influenza prevention efforts and facilitate intervention impact assessment measurement in pediatric SOT recipients.

Clinical characteristics and outcomes of children with single or co-detected rhinovirus-associated acute respiratory infection in Middle Tennessee.

BACKGROUND: Rhinovirus (RV) is one of the most common etiologic agents of acute respiratory infection (ARI), which is a leading cause of morbidity and mortality in young children. The clinical significance of RV co-detection with other respiratory viruses, including respiratory syncytial virus (RSV), remains unclear. We aimed to compare the clinical characteristics and outcomes of children with ARI-associated RV-only detection and those with RV co-detection-with an emphasis on RV/RSV co-detection. METHODS: We conducted a prospective viral surveillance study (11/2015-7/2016) in Nashville, Tennessee. Children < 18 years old who presented to the emergency department (ED) or were hospitalized with fever and/or respiratory symptoms of < 14 days duration were eligible if they resided in one of nine counties in Middle Tennessee. Demographics and clinical characteristics were collected by parental interviews and medical chart abstractions. Nasal and/or throat specimens were collected and tested for RV, RSV, metapneumovirus, adenovirus, parainfluenza 1-4, and influenza A-C using reverse transcription quantitative polymerase chain reaction assays. We compared the clinical characteristics and outcomes of children with RV-only detection and those with RV co-detection using Pearson's χ2 test for categorical variables and the two-sample t-test with unequal variances for continuous variables. RESULTS: Of 1250 children, 904 (72.3%) were virus-positive. RV was the most common virus (n = 406; 44.9%), followed by RSV (n = 207; 19.3%). Of 406 children with RV, 289 (71.2%) had RV-only detection, and 117 (28.8%) had RV co-detection. The most common virus co-detected with RV was RSV (n = 43; 36.8%). Children with RV co-detection were less likely than those with RV-only detection to be diagnosed with asthma or reactive airway disease both in the ED and in-hospital. We did not identify differences in hospitalization, intensive care unit admission, supplemental oxygen use, or length of stay between children with RV-only detection and those with RV co-detection. CONCLUSION: We found no evidence that RV co-detection was associated with poorer outcomes. However, the clinical significance of RV co-detection is heterogeneous and varies by virus pair and age group. Future studies of RV co-detection should incorporate analyses of RV/non-RV pairs and include age as a key covariate of RV contribution to clinical manifestations and infection outcomes.

Sex differences in cancer incidence and mortality among patients managed at King Hussein Cancer Center.

We investigated if female survival advantage trends in cancer are consistent within Jordanian patients with cancer across different age groups and nonsex specific cancer types. We explored the King Hussein Cancer Center registry for primary malignant tumors from 2006 to 2019. The registry (n = 16 454) was stratified into three groups based on age: children (<15 years), adolescents and young adults (AYA) (modified; 15-49 years), and older adults (≥50 years). Kaplan-Meier analysis was used to estimate the 5-year all-site cancer-specific survival probabilities, which were compared using the log-rank test by sex and age group. Out of 16 454 eligible records, 2286 (13.9%) were children, 5975 (36.3%) were AYAs, and 8193 (49.8%) were older adults. Males outnumbered females 10 339 (62.8%) to 6115 (37.2%). The 5-year OS rates were 74.0% (71.6%-76.4%) and 72.7% (69.9%-75.5%) for pediatric males and females, respectively, 57.3% (55.6%-59.0%) and 64.5% (62.6%-66.4%) for male and female AYAs, respectively, and 37.5% (36.2%-38.9%) and 44.2% (42.3%-46.2%) for older adult males and females, respectively. Females demonstrated significantly better overall survival in the AYA and older adults' groups. In conclusion, females exhibit a survival advantage in terms of nonsex specific cancers. This advantage peaks at the AYA age stratum and mitigates thereafter. Further studies are warranted to examine the etiological factors behind such discrepancy on a site-by-site basis so that sex-specific interventions can be designed and validated.

Clinical presentations of adult and pediatric SARS-CoV-2-positive cases in a community cohort, Nashville, Tennessee.

Compared to adults, the prevalence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) illness in children has been lower and less severe. However, reports comparing SARS-CoV-2 infection among children and adults are limited. As part of our longitudinal cohort study of adults and children with SARS-CoV-2 infection and their household contacts in Nashville, Tennessee, we compared the clinical characteristics and outcomes of SARS-CoV-2 infections between children and adults. Children were more likely to be asymptomatically infected and had a shorter illness duration compared to adults. The differences observed in clinical presentation across ages may inform symptom-specific testing, screening, and management algorithms.

Clinical characteristics, outcomes, and seasonality of acute respiratory infection associated with single and codetected rhinovirus species among hospitalized children in Amman, Jordan.

Rhinovirus (RV)-specific surveillance studies in the Middle East are limited. Therefore, we aimed to study the clinical characteristics, outcomes, and seasonality of RV-associated acute respiratory infection among hospitalized young children in Jordan. We conducted a prospective viral surveillance study and enrolled children <2 years old admitted to a large public hospital in Amman, Jordan (2010-2013). Demographic and clinical data were collected by structured interviews and chart abstractions. Nasal and/or throat swabs were collected and tested for a panel of respiratory viruses, and RV genotyping and speciation was performed. At least one virus was detected in 2641/3168 children (83.4%). RV was the second most common virus detected (n = 1238; 46.9%) and was codetected with another respiratory virus in 730 cases (59.0%). Children with RV codetection were more likely than those with RV-only detection to have respiratory distress but had similar outcomes. RV-A accounted for about half of RV-positive cases (54.7%), while children with RV-C had a higher frequency of wheezing and reactive airway disease. RV was detected year-round and peaked during winter. In conclusion, though children with RV codetection had worse clinical findings, neither codetection nor species affected most clinical outcomes.

Incidental finding of an aberrant left pulmonary artery, an aberrant right subclavian artery, and a tracheal bronchus in an adult woman with a meningioma and a history of medulloblastoma.

The aberrant left pulmonary artery and the aberrant right subclavian artery are rare congenital vascular anomalies, and the tracheal bronchus is a rare congenital respiratory anomaly. A 33-year-old female patient, with a history of desmoplastic medulloblastoma, was surgically treated at our hospital for a meningioma. On the second postoperative day, the patient complained of shortness of breath and chest pain. Contrast-enhanced multislice computed tomography was negative for pulmonary embolism, but incidentally revealed all three congenital anomalies. In our report, we detail this exceedingly rare case.

An intronic single-nucleotide polymorphism (rs13217795) in FOXO3 is associated with asthma and allergic rhinitis: a case-case-control study.

BACKGROUND: Asthma and allergic rhinitis are respiratory diseases with a significant global burden. Forkhead box O3 (FOXO3) is a gene involved in the etiology of a number of respiratory diseases. The objective of this study is to assess the association of rs13217795, an intronic FOXO3 single-nucleotide polymorphism, with asthma and allergic rhinitis. METHODS: In this case-case-control genetic association study, genotyping was conducted using the PCR-RFLP method. Genotype-based associations were investigated under the general, recessive, and dominant models of disease penetrance using binomial logistic regression; and, allele-based associations were tested using Pearson's chi-squared test. RESULTS: The final study population consisted of 94 controls, 124 asthmatics, and 110 allergic rhinitis patients. The general and recessive models of disease penetrance were statistically significant for both case-control comparisons. Under the general model, the odds of the asthma phenotype were 1.46 (0.64 to 3.34) and 3.42 (1.37 to 8.57) times higher in heterozygotes and derived allele homozygotes, respectively, compared to ancestral allele homozygotes. The corresponding odds ratios for the allergic rhinitis phenotype were 1.05 (0.46 to 2.40) and 2.35 (0.96 to 5.73), respectively. The dominant model of disease penetrance was not statistically significant. The minor allele in all study groups was the ancestral allele, with a frequency of 0.49 in controls. There was no deviation from Hardy-Weinberg equilibrium in controls. Both case-control allele-based associations were statistically significant. CONCLUSIONS: Herein we present the first report of the association between rs13217795 and allergic rhinitis, and the first independent verification of the association between rs13217795 and asthma. Marker selection in future genetic association studies of asthma and allergic rhinitis should include functional polymorphisms in linkage disequilibrium with rs13217795.

Lymph node ratio is a more robust predictor of overall survival than N stage in stage III colorectal adenocarcinoma.

BACKGROUND: Lymph node ratio (LNR) may offer superior prognostic stratification in colorectal adenocarcinoma compared with N stage. However, candidate cutoff ratios require validation. We aimed to study the prognostic significance of LNR and its optimal cutoff ratio. METHODS: We reviewed the pathology records of all patients with stage III colorectal adenocarcinoma who were managed at the King Hussein Cancer Center between January 2014 and December 2019. We then studied the clinical characteristics of the patients, correlates of lymph node count, prognostic significance of positive lymph nodes, and value of sampling additional lymph nodes. RESULTS: Among 226 included patients, 94.2% had ≥ 12 lymph nodes sampled, while 5.8% had < 12 sampled lymph nodes. The median number of lymph nodes sampled varied according to tumor site, neoadjuvant therapy, and the grossing pathologist's level of training. According to the TNM system, 142 cases were N1 (62.8%) and 84 were N2 (37.2%). Survival distributions differed according to LNR at 10% (p = 0.022), and 16% (p < 0.001), but not the N stage (p = 0.065). Adjusted Cox-regression analyses demonstrated that both N stage and LNR at 10% and 16% predicted overall survival (p = 0.044, p = 0.010, and p = 0.001, respectively). CONCLUSIONS: LNR is a robust predictor of overall survival in patients with stage III colorectal adenocarcinoma. At a cutoff ratio of 0.10 and 0.16, LNR offers better prognostic stratification in comparison with N stage and is less susceptible to variation introduced by the number of lymph nodes sampled, which is influenced both by clinical variables and grossing technique.

Evaluating Acute Viral Gastroenteritis Severity: Modified Vesikari and Clark Scoring Systems.

OBJECTIVE: Acute gastroenteritis (AGE) is the second leading cause of death in children worldwide. Objectively evaluating disease severity is critical for assessing future interventions. We used data from a large, prospective surveillance study to assess risk factors associated with severe presentation using modified Vesikari score (MVS) and Clark score (CS) of severity. METHODS: From December 1, 2012 to June 30, 2016, AGE surveillance was performed for children between 15 days and 17 years old in the emergency, inpatient, and outpatient settings at Vanderbilt's Monroe Carell Jr. Children's Hospital in Nashville, TN. Stool specimens were tested for norovirus, sapovirus, rotavirus, and astrovirus. We compared demographic and clinical characteristics, along with the MVS and CS, by viral detection status and by setting. RESULTS: Of the 6309 eligible children, 4216 (67%) were enrolled, with 3256 (77%) providing a stool specimen. The median age was 1.9 years, 52% were male, and 1387 (43%) of the stool samples were virus positive. Younger age, male sex, hospitalization, and rotavirus detection were significantly associated with higher mean MVS and CS. Non-Hispanic Black race and ethnicity was associated with a lower mean MVS and CS as compared with non-Hispanic white race and ethnicity. Prematurity and enrollment in the ED were associated with higher mean CS. The 2 scoring systems were highly correlated. CONCLUSIONS: Rotavirus continues to be associated with more severe pediatric illness compared with other viral causes of AGE. MVS and CS systems yielded comparable results and can be useful tools to assess AGE severity.

Provider-ordered viral testing and antibiotic administration practices among children with acute respiratory infections across healthcare settings in Nashville, Tennessee.

Objective: Evaluate the association between provider-ordered viral testing and antibiotic treatment practices among children discharged from an ED or hospitalized with an acute respiratory infection (ARI). Design: Active, prospective ARI surveillance study from November 2017 to February 2020. Setting: Pediatric hospital and emergency department in Nashville, Tennessee. Participants: Children 30 days to 17 years old seeking medical care for fever and/or respiratory symptoms. Methods: Antibiotics prescribed during the child's ED visit or administered during hospitalization were categorized into (1) None administered; (2) Narrow-spectrum; and (3) Broad-spectrum. Setting-specific models were built using unconditional polytomous logistic regression with robust sandwich estimators to estimate the adjusted odds ratios and 95% confidence intervals between provider-ordered viral testing (ie, tested versus not tested) and viral test result (ie, positive test versus not tested and negative test versus not tested) and three-level antibiotic administration. Results: 4,107 children were enrolled and tested, of which 2,616 (64%) were seen in the ED and 1,491 (36%) were hospitalized. In the ED, children who received a provider-ordered viral test had 25% decreased odds (aOR: 0.75; 95% CI: 0.54, 0.98) of receiving a narrow-spectrum antibiotic during their visit than those without testing. In the inpatient setting, children with a negative provider-ordered viral test had 57% increased odds (aOR: 1.57; 95% CI: 1.01, 2.44) of being administered a broad-spectrum antibiotic compared to children without testing. Conclusions: In our study, the impact of provider-ordered viral testing on antibiotic practices differed by setting. Additional studies evaluating the influence of viral testing on antibiotic stewardship and antibiotic prescribing practices are needed.

Clinical prediction model: Multisystem inflammatory syndrome in children versus Kawasaki disease.

BACKGROUND: Multisystem inflammatory syndrome in children (MIS-C) is a rare but serious complication of severe acute respiratory syndrome coronavirus 2 infection. Features of MIS-C overlap with those of Kawasaki disease (KD). OBJECTIVE: The study objective was to develop a prediction model to assist with this diagnostic dilemma. METHODS: Data from a retrospective cohort of children hospitalized with KD before the coronavirus disease 2019 pandemic were compared to a prospective cohort of children hospitalized with MIS-C. A bootstrapped backwards selection process was used to develop a logistic regression model predicting the probability of MIS-C diagnosis. A nomogram was created for application to individual patients. RESULTS: Compared to children with incomplete and complete KD (N = 602), children with MIS-C (N = 105) were older and had longer hospitalizations; more frequent intensive care unit admissions and vasopressor use; lower white blood cell count, lymphocyte count, erythrocyte sedimentation rate, platelet count, sodium, and alanine aminotransferase; and higher hemoglobin and C-reactive protein (CRP) at admission. Left ventricular dysfunction was more frequent in patients with MIS-C, whereas coronary abnormalities were more common in those with KD. The final prediction model included age, sodium, platelet count, alanine aminotransferase, reduction in left ventricular ejection fraction, and CRP. The model exhibited good discrimination with AUC 0.96 (95% confidence interval: [0.94-0.98]) and was well calibrated (optimism-corrected intercept of -0.020 and slope of 0.99). CONCLUSIONS: A diagnostic prediction model utilizing admission information provides excellent discrimination between MIS-C and KD. This model may be useful for diagnosis of MIS-C but requires external validation.

Immunophenotypic predictors of influenza vaccine immunogenicity in pediatric hematopoietic cell transplant recipients.

ABSTRACT: Pediatric hematopoietic cell transplant (HCT) recipients exhibit poor serologic responses to influenza vaccination early after transplant. To facilitate the optimization of influenza vaccination timing, we sought to identify B- and T-cell subpopulations associated with influenza vaccine immunogenicity in this population. We used mass cytometry to phenotype peripheral blood mononuclear cells collected from pediatric HCT recipients enrolled in a multicenter influenza vaccine trial comparing high- and standard-dose formulations over 3 influenza seasons (2016-2019). We fit linear regression models to estimate relationships between immune cell subpopulation numbers before vaccination and prevaccination to postvaccination geometric mean fold rises in antigen-specific (A/H3N2, A/H1N1, and B/Victoria) serum hemagglutination inhibition antibody titers (28-42 days, and ∼6 months after 2 doses). For cell subpopulations identified as predictive of a response to all 3 antigens, we conducted a sensitivity analysis including time after transplant as an additional covariate. Among 156 HCT recipients, we identified 33 distinct immune cell subpopulations; 7 significantly predicted responses to all 3 antigens 28 to 42 days after a 2-dose vaccine series, irrespective of vaccine dose. We also found evidence that baseline absolute numbers of naïve B cells, naïve CD4+ T cells, and circulating T follicular helper cells predicted peak and sustained vaccine-induced titers irrespective of dose or timing of posttransplant vaccine administration. In conclusion, several B- and T-cell subpopulations predicted influenza vaccine immunogenicity in pediatric HCT recipients. This study provides insights into the immune determinants of vaccine responses and may help guide the development of tailored vaccination strategies for this vulnerable population.