Lower risk of Multi-system inflammatory syndrome in children (MIS-C) with the omicron variant

The plasma proteome differentiates the multisystem inflammatory syndrome in children (MIS-C) from children with SARS-CoV-2 negative sepsis

BACKGROUND

The Multi-System Inflammatory Syndrome in Children (MIS-C) can develop several weeks after SARS-CoV-2 infection and requires a distinct treatment protocol. Distinguishing MIS-C from SARS-CoV-2 negative sepsis (SCNS) patients is important to quickly institute the correct therapies. We performed targeted proteomics and machine learning analysis to identify novel plasma proteins of MIS-C for early disease recognition.

METHODS

A case-control study comparing the expression of 2,870 unique blood proteins in MIS-C versus SCNS patients, measured using proximity extension assays. The 2,870 proteins were reduced in number with either feature selection alone or with a prior COMBAT-Seq batch effect adjustment. The leading proteins were correlated with demographic and clinical variables. Organ system and cell type expression patterns were analyzed with Natural Language Processing (NLP).

RESULTS

The cohorts were well-balanced for age and sex. Of the 2,870 unique blood proteins, 58 proteins were identified with feature selection (FDR-adjusted P < 0.005, P < 0.0001; accuracy = 0.96, AUC = 1.00, F1 = 0.95), and 15 proteins were identified with a COMBAT-Seq batch effect adjusted feature selection (FDR-adjusted P < 0.05, P < 0.0001; accuracy = 0.92, AUC = 1.00, F1 = 0.89). All of the latter 15 proteins were present in the former 58-protein model. Several proteins were correlated with illness severity scores, length of stay, and interventions (LTA4H, PTN, PPBP, and EGF; P < 0.001). NLP analysis highlighted the multi-system nature of MIS-C, with the 58-protein set expressed in all organ systems; the highest levels of expression were found in the digestive system. The cell types most involved included leukocytes not yet determined, lymphocytes, macrophages, and platelets.

CONCLUSIONS

The plasma proteome of MIS-C patients was distinct from that of SCNS. The key proteins demonstrated expression in all organ systems and most cell types. The unique proteomic signature identified in MIS-C patients could aid future diagnostic and therapeutic advancements, as well as predict hospital length of stays, interventions, and mortality risks.

Short-term and medium-term clinical outcomes of multisystem inflammatory syndrome in children: a prospective observational cohort study

BACKGROUND

Even though the incidence of Multisystem Inflammatory Syndrome in children (MIS-C) is decreasing cases are still reported across the world. Studying the consequences of MIS-C enhances our understanding of the disease's prognosis. The objective of this study was to assess short- and medium-term clinical outcomes of MIS-C.

METHODS

Prospective observational cohort study at Municipal Children's Hospital Morozovskaya, Moscow, Russia. All children meeting the Royal College of Paediatrics and Child Health (RCPCH), Centers for Disease Control and Prevention (CDC), or the World Health Organization (WHO) MIS-C case definition admitted to the hospital between 17 May and 26 October 2020 were included in the study. All survivors were invited to attend a clinic at 2 and 6 weeks after hospital discharge.

RESULTS

37 children median age 6 years (interquartile range [IQR] 3.3-9.4), 59.5% (22/37) boys were included in the study. 48.6% (18/37) of patients required ICU care. One child died. All children had increased levels of systemic inflammatory markers during the acute event. Echocardiographic investigations identified abnormal findings in 35.1% (13/37) of children. 5.6% (2/36) of children were presenting with any symptoms six weeks after discharge. By six weeks the inflammatory markers were within the reference norms in all children. The echocardiographic evaluation showed persistent coronary dilatation in one child.

CONCLUSIONS

Despite the severity of their acute MIS-C, the majority of children in our cohort fully recovered with none having elevated laboratory markers of inflammation at 6 weeks, few (< 10%) reporting persistent symptoms at 6 weeks, and only one with persistent echocardiographic abnormalities.

Clinical Syndromes Related to SARS-CoV-2 Infection and Vaccination in Pediatric Age: A Narrative Review

This narrative review aims to report the main clinical manifestations, therapeutic strategies, outcomes, and complications of acute SARS-CoV-2 infection in childhood and to summarize the data relating the SARS-CoV-2 vaccination efficacy and safety in pediatric age. SARS-CoV-2 infection mostly occurs asymptomatically in the pediatric population, while multisystem inflammatory syndrome in children (MIS-C) represents the most severe coronavirus disease 2019 (COVID-19)-related illness, a life-threatening event with a high morbidity rate. After the development of SARS-CoV-2 vaccines and their subsequent approval in children, the rate of infection as well as the number of its related complications have shown a drastic decrease. Fully vaccinated children are protected from the risk of developing a severe disease and a similar protective role has been observed in the reduction of complications, in particular MIS-C. However, long-lasting immunity has not been demonstrated, booster doses have been required, and reinfection has been observed. With regards to vaccine safety, adverse events were generally mild to moderate in all age groups: local adverse events were the most commonly reported. Nevertheless, a potential association between SARS-CoV-2 vaccine and the subsequent development of inflammatory manifestations has been suggested. Myocarditis has rarely been observed following vaccination; it appeared to be more frequent among adolescent males with a mild clinical course leading to a complete recovery. SARS-CoV-2 vaccine-related MIS-C cases have been described, although a univocal definition and an exact time interval with respect to vaccination has not been reported, thus not establishing a direct causal link. Current evidence about COVID-19 vaccination in children and adolescents suggest that benefits outweigh potential risks. Long-term data collection of the post-authorization safety surveillance programs will better define the real incidence of SARS-CoV-2 vaccine-related complications in the pediatric population.

Demographic, clinical and laboratory differences between paediatric acute COVID-19 and PIMS-TS-results from a single centre study in the UK

Background

Paediatric symptomatic SARS-CoV-2 infections associate with two presentations, acute COVID-19 and paediatric inflammatory multisystem syndrome temporally associated with SARS-CoV-2 (PIMS-TS). Phenotypic comparisons, and reports on predictive markers for disease courses are sparse and preliminary.

Methods

A chart review of COVID-19 and PIMS-TS patients (≤19 years) admitted to Alder Hey Children's NHS Foundation Trust, a tertiary centre in the North-West of England, was performed (02/2020-09/2022).

Results

A total of 161 symptomatic COVID-19 and 50 PIMS-TS patients were included. Peaks in admissions of patients with PIMS-TS occurred approximately 4 weeks after those for acute COVID-19. The incidence of in-patients with PIMS-TS reduced over time, and there were no admissions after February 2022. When compared to acute COVID-19, PIMS-TS patients were older (median: 10.3 years vs. 2.03 years; p < 0.001). There were no differences in gender distribution, but minority ethnicities were over-represented among PIMS-TS patients. Regional ethnic distribution was reflected among acute COVID-19 patients (66% vs. 84.5% White Caucasian, p = 0.01). Pre-existing comorbidities were more common among acute COVID-19 patients (54.7% vs. 8%, p < 0.001). PIMS-TS patients more commonly presented with abdominal symptoms (92% vs. 50.3%), neurological symptoms (28% vs. 10.6%) and skin rashes (72% vs. 16.8%), (p ≤ 0.01) when compared with acute COVID-19, where respiratory symptoms were more common (51.6% vs. 32%, p = 0.016). PIMS-TS more frequently required intensive care admission (64% vs. 16.8%), and inotropic support (64% vs. 9.3%) (all p < 0.05). More deaths occurred among acute COVID-19 patients [0 vs. 7 (4.4%)], with 5/7 (71%) in the context of pre-existing comorbidities. When compared to acute COVID-19, PIMS-TS patients exhibited more lymphopenia and thrombocytopenia, a more pronounced acute phase reaction, and more hyponatraemia (p < 0.05). Partial least square discriminant analysis of routine laboratory parameters allowed (incomplete) separation of patients at diagnosis, and variable importance projection (VIP) scoring revealed elevated CRP and low platelets as the most discriminatory parameters.

Conclusion

Admissions for PIMS-TS reduced with increasing seroconversion rates in the region. Young age and pre-existing comorbidities associate with hospital admission for acute COVID-19. While PIMS-TS may present more acutely with increased need for intensive care, acute COVID-19 had an increased risk of mortality in this cohort.

Epidemiology and Severity of Illness of MIS-C and Kawasaki Disease During the COVID-19 Pandemic

BACKGROUND AND OBJECTIVES

Multisystem inflammatory syndrome in children (MIS-C) is a novel, severe condition following severe acute respiratory syndrome coronavirus 2 infection. Large epidemiologic studies comparing MIS-C to Kawasaki disease (KD) and evaluating the evolving epidemiology of MIS-C over time are lacking. We sought to understand the illness severity of MIS-C compared with KD and evaluate changes in MIS-C illness severity over time during the coronavirus disease 2019 pandemic compared with KD.

METHODS

We included hospitalizations of children with MIS-C and KD from April 2020 to May 2022 from the Pediatric Health Information System administrative database. Our primary outcome measure was the presence of shock, defined as the use of vasoactive/inotropic cardiac support or extracorporeal membrane oxygenation. We examined the volume of MIS-C and KD hospitalizations and the proportion of hospitalizations with shock over time using 2-week intervals. We compared the proportion of hospitalizations with shock in MIS-C and KD patients over time using generalized estimating equations adjusting for hospital clustering and age, with time as a fixed effect.

RESULTS

We identified 4868 hospitalizations for MIS-C and 2387 hospitalizations for KD. There was a higher proportion of hospitalizations with shock in MIS-C compared with KD (38.7% vs 5.1%). In our models with time as a fixed effect, we observed a significant decrease in the odds of shock over time in MIS-C patients (odds ratio 0.98, P < .001) but not in KD patients (odds ratio 1.00, P = .062).

CONCLUSIONS

We provide further evidence that MIS-C is a distinct condition from KD. MIS-C was a source of lower morbidity as the pandemic progressed.

Change in Severity and Clinical Manifestation of MIS-C Over SARS-CoV-2 Variant Outbreaks in Korea

BACKGROUND

There is difference in the incidence of multi-system inflammatory syndrome in children (MIS-C) in patients with different variants of severe acute respiratory syndrome coronavirus 2, however, little is known about the epidemiology in Asian countries. We investigated and compared the epidemiology of the MIS-C during omicron-dominant period with that of previous periods in South Korea.

METHODS

We obtained clinical, epidemiological and laboratory data on MIS-C cases from national MIS-C surveillance in South Korea. We defined pre-delta period as January 2020-May 2021; delta period as June 2021-December 2021; and omicron period as January 2022-April 2022. We describe the clinical characteristics and outcomes of MIS-C patients by period.

RESULTS

A total of 91 cases were assessed to be MIS-C cases. Number of MIS-C cases have increased from six cases during pre-delta period to 66 cases during omicron period, while the incidence rate (the number of MIS-C cases per 100,000 cases of reported coronavirus disease 2019) has decreased from 38.5 cases per 100,000 (95% confidence interval [CI], 14.1-83.9) during pre-delta period to 1.6 cases per 100,000 (95% CI, 1.2-2.0) during omicron periods. During pre-delta period, 66.7% and 100% had hypotension and gastrointestinal involvement, respectively; while during omicron period, 12.1% and 6.1% had such clinical manifestations. Fifty percent of pre-delta MIS-C patients were taken intensive care unit (ICU) cares, while 10.6% of patients during omicron periods were in ICUs.

CONCLUSION

Omicron period were associated with less severe clinical manifestation compared to pre-delta and delta periods. Although incidence rate of MIS-C was lower for the omicron period than pre-delta and delta periods, number of patients reported with MIS-C may pose a substantial clinical burden.

Development of a Model to Identify Febrile Children at Low Risk for Multisystem Inflammatory Syndrome

OBJECTIVES

The case definition for multisystem inflammatory syndrome in children (MIS-C) is broad and encompasses symptoms and signs commonly seen in children with fever. Our aim was to identify clinical predictors that, independently or in combination, identify febrile children presenting to the emergency department (ED) as low risk for MIS-C.

METHODS

We conducted a retrospective single-center study of otherwise healthy children 2 months to 20 years of age presenting to the ED with fever and who had a laboratory evaluation for MIS-C between April 15, 2020, and October 31, 2020. We excluded children with a diagnosis of Kawasaki disease. Our outcome was an MIS-C diagnosis defined by the Centers for Disease Control and Prevention criteria. We conducted multivariable logistic regression analyses to identify variables independently associated with MIS-C.

RESULTS

Thirty-three patients with and 128 patients without MIS-C were analyzed. Of those with MIS-C, 16 of 33 (48.5%) had hypotension for age, signs of hypoperfusion, or required ionotropic support. Four variables were independently associated with the presence of MIS-C; known or suspected SARS CoV-2 exposure (adjusted odds ratio [aOR], 4.0; 95% confidence interval [CI], 1.4-11.9) and the following 3 symptoms and signs: abdominal pain on history (aOR, 4.8; 95% CI, 1.7-15.0), conjunctival injection (aOR, 15.2; 95% CI, 5.4-48.1), and rash involving the palms or soles (aOR, 12.2; 95% CI, 2.4-69.4). Children were at low risk of MIS-C if none of the 3 symptoms or signs were present (sensitivity 87.9% [95% CI, 71.8-96.6]; specificity 62.5% [53.5-70.9], negative predictive value 95.2% [88.3-98.7]). Of the 4 MIS-C patients without any of these 3 factors, 2 were ill-appearing in the ED and the other 2 had no cardiovascular involvement during their clinical course.

CONCLUSIONS

A combination of 3 clinical symptoms and signs had moderate to high sensitivity and high negative predictive value for identifying febrile children at low risk of MIS-C. If validated, these factors could aid clinicians in determining the need to obtain or forego an MIS-C laboratory evaluation during SARS-CoV-2 prevalent periods in febrile children.

Considerations for vaccinating children against COVID-19

COVID-19 vaccines have been introduced in children and adolescents in many countries. However, high levels of community transmission and infection-derived immunity make the decision to introduce COVID-19 vaccination of children in countries yet to do so particularly challenging. For example, other vaccine preventable diseases, including measles and polio, generally have far higher childhood morbidity and mortality in low-income and middle-income countries (LMICs) than COVID-19, and coverage with these vaccines has declined during the pandemic. Many countries are yet to introduce pneumococcal conjugate and rotavirus vaccines for children, which prevent common causes of childhood death, or human papillomavirus vaccine for adolescents. The Pfizer and Moderna COVID-19 vaccines that have been widely tested in children and adolescents have a positive risk-benefit profile. However, the benefit is less compared with other life-saving vaccines in this age group, particularly in LMICs and settings with widespread infection-derived immunity. The resources required for rollout may also pose a considerable challenge in LMICs. In this paper, we describe COVID-19 in children, with a focus on LMICs, and summarise the published literature on safety, efficacy and effectiveness of COVID-19 vaccination in children and adolescents. We highlight the complexity of decision-making regarding COVID-19 vaccination of children now that most of this low-risk population benefit from infection-derived immunity. We emphasise that at-risk groups should be prioritised for COVID-19 vaccination; and that if COVID-19 vaccines are introduced for children, the opportunity should be taken to improve coverage of routine childhood vaccines and preventative healthcare. Additionally, we highlight the paucity of epidemiological data in LMICs, and that for future epidemics, measures need to be taken to ensure equitable access to safe and efficacious vaccines before exposure to infection.

Multisystem Inflammatory Syndrome in New Zealand Children

New Zealand (NZ) initially adopted an elimination approach to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Pre-Omicron variant, the NZ pediatric population was immunologically naïve to SARS-CoV-2. This study, utilizing national data sources, describes the NZ incidence of multisystem inflammatory syndrome in children (MIS-C) following infection with the Omicron variant. MIS-C incidence was 1.03 of 100,000 age-specific population and 0.04 of 1000 recorded SARS-CoV-2 infections.

Multi-Inflammatory Syndrome in Children (MIS-C) in 2023: Is It Time to Forget about It?

Multisystem inflammatory syndrome in children (MIS-C) is defined as a clinically serious condition requiring hospitalization involving fever, multi-system organ dysfunction, and an increase in inflammatory biomarkers. The syndrome was originally described as a post-infectious complication of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, which usually causes COVID-19. During the COVID-19 pandemic, not only did the virus undergo mutations but vaccines against SARS-CoV-2 were also developed. Both these conditions led to a decrease in the incidence of MIS-C. This narrative review summarizes the recent updates for MIS-C, particularly regarding the change in incidence, the link between the SARS-CoV-2 vaccine and MIS-C, and new updates of MIS-C treatments.

COVID-19 related ICU admissions in paediatric and young adult patients in Australia: a national case series 2020-2022

Background

COVID-19 pandemic research efforts have focused on disease phenotypes in adults. A distinct spectrum of illness has been documented in paediatric populations. We aimed to review paediatric intensive care unit (ICU) admissions in Australia, across differing variant predominant phases of the pandemic.

Methods

Data reported to the Short PeRiod IncideNce sTudy of Severe Acute Respiratory Infection (SPRINT-SARI) Australia, across 49 ICUs from February 2020 to June 2022 were extracted. We defined 'child' as patients aged <12 years, 'adolescent' as patients aged 12-17 years, and 'young adult' as patients aged 18-25 years.

Findings

We identified 226 paediatric ICU admissions with COVID-19, representing 3.9% of ICU admissions across the study period. Comorbidity was present in 34.6% of children, 51.4% of adolescents, and 48.7% of young adults. The need for respiratory support was highest in young adults. While 28.3% of patients <18 years required invasive ventilation, in-hospital mortality in paediatric patients was 3.6%. During the Omicron period, there was an increase in the annualised incidence of age-specific COVID-19 ICU admissions per 100,000 population, albeit a decrease in the incidence per 1000 SARS-CoV-2 notifications.

Interpretation

This study demonstrated an appreciable burden of COVID-19 in paediatric patients. Adolescent patients presented phenotypically similar to young adults, however, illness severity was lower in younger cohorts. The Omicron phase of the pandemic demonstrated an increased age-specific population incidence of COVID-19 ICU admissions, albeit a reduced incidence when based on SARS-CoV-2 notifications.

Funding

SPRINT-SARI Australia is supported by the Department of Health, Commonwealth of Australia [Standing Deed SON60002733].

Epidemiology, clinical characteristics and outcomes of multisystem inflammatory syndrome in children

BACKGROUND

We describe the epidemiology, clinical characteristics, and outcomes of multisystem inflammatory syndrome in children (MIS-C) among children from Negeri Sembilan, Malaysia.

METHODS

A retrospective, multicentre, observational study was performed among children ≤15 years old who were hospitalized for MIS-C between January 18, 2021 and June 30, 2023. The incidence of MIS-C was estimated using reported SARS-CoV-2 cases and census population data. Descriptive analyses were used to summarize the clinical presentation and outcomes.

RESULTS

The study included 53 patients with a median age of 5.7 years (IQR 1.8-8.7 years); 75.5% were males. The overall incidence of MIS-C was approximately 5.9 cases per 1,000,000 person-months. Pediatric intensive care unit (PICU) admission was required for 22 (41.5%) patients. No mortalities were recorded. Children aged 6-12 years were more likely to present with cardiac dysfunction/shock (odds ratio [OR] 5.43, 95% confidence interval [CI] 1.67-17.66), whereas children below 6 years were more likely to present with a Kawasaki disease phenotype (OR 5.50, 95% CI 1.33-22.75). Twenty patients (37.7%) presented with involvement of at least four organ systems, but four patients (7.5%) demonstrated single-organ system involvement.

CONCLUSION

An age-based variation in the clinical presentation of MIS-C was demonstrated. Our findings suggest MIS-C could manifest in a spectrum, including single-organ involvement. Despite the high requirement for PICU admission, the prognosis of MIS-C was favorable, with no recorded mortalities.

Multisystem inflammatory syndrome in children during the first two years of the COVID-19 pandemic in Luxembourg

Objective

Estimate the incidence of multisystem inflammatory syndrome (MIS-C) in children (0-15 years), the role of SARS-CoV-2 variants during the first two years of COVID-19 pandemic in Luxembourg; and describe the demographic, biological and clinical characteristics of the patients.

Method

Observational retrospective cohort study. Cases between March 2020 and February 2022 were ascertained from the national registry of MIS-C cases by a retrospective review of medical records. Reported SARS-CoV-2 infections were obtained from the national COVID-19 surveillance system. We calculated monthly MIS-C incidence, the ratio between MIS-C and SARS-CoV-2 infections and associated rate ratios by the periods corresponding to the circulation of different variants.

Results

18 children were diagnosed with MIS-C among 35,200 reported infections. The incidence rate of MIS-C was 7.2 [95% confidence interval (CI) 4.5-11.4] per 1,000,000 person-months. A higher incidence of MIS-C was observed between September and December 2021, corresponding to the circulation of the Delta variant than during the first year of the pandemic (RR 3.6, 95% CI, 1.1-12.3). The lowest rate of MIS-C per infection was observed during the Omicron (RR 0.17, 95% CI, 0.03-0.82). Median age at diagnosis was 6.5 years. Previously healthy children made up 88% of MIS-C cases, none were vaccinated against SARS-CoV-2. 33% required intensive care. All patients recovered fully.

Conclusions

MIS-C incidence and MIS-C risk per infection changed significantly over time during the first two years of COVID-19 pandemic. Monitoring of MIS-C incidence in future SARS-CoV-2 waves will be essential to guide public health interventions and vaccination policies for children.

Analysis of the impact of the SARS-CoV-2 infection on the pediatric population hospitalized during the pandemic in the Greater Paris University Hospitals

Background

The clinical characteristics, disease progression and outcome in children affected by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection appear significantly milder compared to older individuals. Nevertheless, the trends in hospitalization and clinical characteristics in the pediatric population seem to be different over time across the different epidemic waves.

Objective

Our aim was to understand the impact of the different COVID-19 variants in the pediatric population hospitalized in the Pediatric Departments of the Public Hospital in the Greater Paris area by the analysis performed with the Assistance Publique-Hopitaux de Paris (AP-HP) Health Data Warehouse.

Methods

This is a retrospective cohort study including 9,163 patients under 18 years of age, hospitalized from 1 March 2020 to 22 March 2022, in the Paris area, with confirmed infection by SARS-CoV-2. Three mutually exclusive groups with decreasing severity (Pediatric Inflammatory Multisystem Syndrome (PIMS), symptomatic infection, mild or asymptomatic infection) were defined and described regarding demography, medical history, complication of the SARS-CoV-2 infection, and treatment during admission. Temporal evolution was described by defining three successive waves (March-September 2020, October 2020-October 2021, and November 2021-March 2022) corresponding to the emergence of the successive variants.

Results

In the study period, 9,163 pediatric patients with SARS-CoV-2 infection were hospitalized in 21 AP-HP hospitals. The number of patients with SARS-CoV-2 infection increased over time for each wave of the pandemic (the mean number of patients per month during the first wave was 332, 322 during the 2nd, and 595 during the third wave). In the medical history, the most associated concomitant disease was chronic respiratory disease. Patients hospitalized during the third wave presented a higher incidence of pulmonary involvement (10.2% compared to 7% and 6.5% during the first and second waves, respectively). The highest incidence of PIMS was observed during the first and second waves (4.2% in the first and second waves compared to 2.3% in the 3rd wave).

Discussion

This analysis highlighted the high incidence of hospitalized children in the Greater Paris Area during the third wave of SARS-CoV-2 pandemic corresponding to the Omicron Covid-19 variant, which is probably an expression of a concomitant SARS-CoV-2, while a decreased incidence of PIMS complication was observed during the same period.