Assessment of Pediatric Admissions for Kawasaki Disease or Infectious Disease During the COVID-19 State of Emergency in Japan

Virus-Induced Host Chemokine CCL2 in COVID-19 Pathogenesis: Potential Prognostic Marker and Target of Anti-Inflammatory Strategy

A wide variety of inflammatory mediators, mainly cytokines and chemokines, are induced during SARS CoV-2 infection. Among these proinflammatory mediators, chemokines tend to play a pivotal role in virus-mediated immunopathology. The C-C chemokine ligand 2 (CCL2), also known as monocyte chemoattractant protein-1 (MCP-1) is a potent proinflammatory cytokine and strong chemoattractant of monocytes, macrophages and CD4+ T cells bearing C-C chemokine receptor type-2 (CCR2). Besides controlling immune cell trafficking, CCL2 is also involved in multiple pathophysiological processes including systemic hyperinflammation associated cytokine release syndrome (CRS), organ fibrosis and blood coagulation. These pathological features are commonly manifested in severe and fatal cases of COVID-19. Given the crucial role of CCL2 in COVID-19 pathogenesis, the CCL2:CCR2 axis may constitute a potential therapeutic target to control virus-induced hyperinflammation and multi-organ dysfunction. Herein we describe recent advances on elucidating the role of CCL2 in COVID-19 pathogenesis, prognosis, and a potential target of anti-inflammatory interventions.

Resurgence of Kawasaki Disease Following Relaxation of Coronavirus Disease 2019 Pandemic Restrictions in Japan

OBJECTIVES

To compare the number and incidence of Kawasaki disease (KD) patients in years 2 through 4 of the coronavirus disease 2019 (COVID-19) pandemic, and determine the impact of 3 years of implementation infection control measures and their subsequent relaxation on the epidemiology of KD in Japan.

STUDY DESIGN

We conducted a population-based, cohort study including consecutive KD patients in Kobe City between 2021 and 2023. We compared the incidence of KD cases, in relation to timing of infection control measures, as well as infectious disease cases based on a regional surveillance system. Data from a previous 2016 through 2020 study were used for comparison.

RESULTS

A total of 566 children with KD were identified during the study period. During the infection control period in 2021 to 2022, the incidence of KD remained low compared with the pre-pandemic level (281.3 and 327.5/100,000 children aged 0-4 years in 2021to 2022 and 2016 through 2019, respectively), but a recovery trend began in the 0-1-year age group. During the relaxation period in 2023, the incidence of KD increased across a wide age range, reaching the highest recorded in Japan (426.7/100,000 children aged 0-4 years), and the median age of onset increased to age 30 months. The resurgence of KD coincided with the patterns for multiple infectious diseases in 2023. The seasonality of KD observed before the pandemic was altered.

CONCLUSIONS

KD resurged in 2023 after relaxation of the prolonged COVID-19 pandemic restrictions in Japan. This phenomenon coincided with the rise of multiple infectious diseases, and supports the pathogenesis of KD being triggered by infectious agents.

Respiratory viral infections and Kawasaki disease: A molecular epidemiological analysis

BACKGROUND/PURPOSE

Recent large-scale epidemiological studies have revealed significant temporal associations between certain viral infections and the subsequent development of Kawasaki disease (KD). Despite these associations, definitive laboratory evidence linking acute or recent viral infections to KD cases remains elusive. The objective of this study is to employ a molecular epidemiological approach to investigate the temporal association between viral infections and the development of KD.

METHODS

We analyzed 2460 patients who underwent the FilmArray® Respiratory Panel test between April 2020 and September 2021.

RESULTS

Following the application of inclusion criteria, 2402 patients were categorized into KD (n = 148), respiratory tract infection (n = 1524), and control groups (n = 730). The KD group exhibited higher positive rates for respiratory syncytial virus (RSV), human rhinovirus/enterovirus (hRV/EV), parainfluenza virus (PIV) 3, and adenovirus (AdV) compared to the control group. Additionally, coinfections involving two or more viruses were significantly more prevalent in the KD group. Notably, RSV-positive, hRV/EV-positive, and PIV3-positive KD patients exhibited a one-month delay in peak occurrence compared to non-KD patients positive for corresponding viruses. In contrast, AdV-positive KD cases did not show a one-month delay in peak occurrence. Moreover, anti-RSV, anti-PIV3, and anti-AdV antibody-positive rates or antibody titers were higher in RSV-, PIV3-, and AdV-positive KD cases, respectively, compared to non-KD cases with the same viral infections.

CONCLUSION

Recent infection with RSV, PIV3, or AdV, occasionally in conjunction with other viruses, may contribute to the pathogenesis of KD as infrequent complications.

Declining Incidence of Kawasaki Disease During the COVID-19 Pandemic: A Time Series Analysis

BACKGROUND

In 2020, Taiwan experienced a dramatic disruption of daily life due to measures aimed at limiting the spread of coronavirus disease 2019 (COVID-19), although domestic COVID-19 cases were extremely rare. This provided a chance to investigate the change of incidence and possible triggers of Kawasaki disease (KD) without the interference of multisystem inflammatory syndrome in children.

METHODS

This population-based study used Taiwan's National Health Insurance Research Database. To detect the change in KD incidence in children less than 6 years old during the period of social distancing policy in 2020, the autoregressive integrated moving average model was used based on seasonal variation and the increasing trend of KD incidence over the past 10 years. The trends in population mobility and common infectious diseases were also analyzed to observe their effects on KD incidence.

RESULTS

The predicted monthly incidence [95% confidence interval (CI)] of KD in April, May and June 2020 were 5.26 (3.58-6.94), 5.45 (3.70-7.20) and 5.41 (3.61-7.21) per 100,000 person-months. The actual observed incidences were 2.41, 2.67 and 2.60 per 100,000 person-months, respectively, representing a 51.2%, 51.0% and 51.9% reduction in incident rates in the 3-month period of stringent COVID-19 mitigation measures. The trend was not proportionate to the profound decline of common infectious cases.

CONCLUSIONS

KD incidence decreased by approximately 50% during the period of stringent COVID-19 mitigation measures in 2020 in Taiwan. Human-to-human contact may be a potential KD trigger, but there are likely other contributing factors aside from infection.

The etiologies of Kawasaki disease

Kawasaki disease (KD) is a systemic vasculitis that affects young children and can result in coronary artery aneurysms. The etiology is currently unknown, but new clues from the epidemiology of KD in Japan, the country of highest incidence, are beginning to shed light on what may trigger this acute inflammatory condition. Additional clues from the global changes in KD incidence during the COVID-19 pandemic, coupled with a new birth cohort study from Japan, point to the potential role of person-to-person transmission of an infectious agent. However, the rising incidence of KD in Japan, with coherent waves across the entire country, points to an increasing intensity of exposure that cannot be explained by person-to-person spread. This Review discusses new and historical observations that guide us toward a better understanding of KD etiology and explores hypotheses and interpretations that can provide direction for future investigations. Once the etiology of KD is determined, accurate diagnostic tests will become available, and new, less expensive, and more effective targeted therapies will likely be possible. Clearly, solving the mystery of the etiologies of KD remains a priority for pediatric research.

Age-Dependent Variations in Kawasaki Disease Incidence in Japan

Importance

The etiology of Kawasaki disease (KD) remains elusive, with immunologic and epidemiologic data suggesting different triggers in individuals who are genetically susceptible. KD remains the most common cause of acquired heart disease in pediatric patients, and Japan is the country of highest incidence, with an increasing number of cases.

Objective

To investigate whether an analysis of the epidemiologic KD record in Japan stratified by age and prefecture (subregion) may yield new clues regarding mechanisms of exposure to etiologic agents associated with KD.

Design, Setting, and Participants

This cross-sectional study was conducted using a dataset of patients with KD with detailed information on location and age at onset created through nationwide surveys of hospitals caring for pediatric patients with KD throughout Japan. Pediatric patients hospitalized in Japan for KD from 1970 to 2020 were included. Data were analyzed from January 2022 to January 2024.

Exposure

Pediatric patients with KD.

Main Outcomes and Measures

The KD dataset was analyzed by patient age (infants [aged <6 months], toddlers [aged 6 to <24 months], children aged 2 years [aged 24 to <36 months], and children and adolescents aged 3 years or older [aged ≥36 months]), with investigations of seasonal cycles, interannual variations, and correlations across regions.

Results

Among 422 528 pediatric patients (243 803 males [57.7%] and 178 732 females [42.3%]; median [IQR] age, 23.69 [11.96-42.65] months), infants, toddlers, and patients aged 3 years or older exhibited different rates of increase in KD incidence, seasonality, and degrees of coherence of seasonality across prefectures. Although the mean (SD) incidence of KD among infants remained relatively stable over the past 30 years compared with older patients (1.00 [0.07] in 1987-1992 to 2.05 [0.11] in 2011-2016), the mean (SD) incidence rate for children and adolescents aged 3 years or older increased 5.2-fold, from 1.00 (0.08) in 1987 to 1992 to 5.17 (0.46) in 2014 to 2019. Patients aged 3 years or older saw a reduction in mean (SD) incidence, from peaks of 5.71 (0.01) in October 2014 through June 2015 and July 2018 through March 2019 to 4.69 (0.11) in 2016 to 2017 (17.8% reduction) not seen in younger children. The seasonal cycle varied by age group; for example, mean (SD) incidence peaked in July and August (5.63 [0.07] cases/100 000 individuals) for infants and in December and January (4.67 [0.13] cases/100 000 individuals) for toddlers. Mean (SD) incidence changed dramatically for toddlers beginning in the early 2010s; for example, the normalized mean (SD) incidence among toddlers for October was 0.74 (0.03) in 1992 to 1995 and 1.10 (0.01) in 2016 to 2019. Across Japan, the seasonal cycle of KD incidence of older children and adolescents exhibited mean (SD) correlation coefficients between prefectures as high as 0.78 (0.14) for prefecture 14 among patients aged 3 years or older, while that of infants was much less (highest mean [SD] correlation coefficient, 0.43 [0.23]).

Conclusions and Relevance

This study found distinct temporal signatures and changing spatial consistency of KD incidence across age groups, suggesting different age-related mechanisms of exposure. Some results suggested that social factors may modulate exposure to etiologic agents of KD; however, the increase in KD incidence in older children coupled with the correlation across prefectures of KD incidence suggest that the intensity of an environmental exposure that triggers KD in this age group may have increased over time.

Kawasaki Disease in the Time of COVID-19 and MIS-C: The International Kawasaki Disease Registry

BACKGROUND

Patients with multisystem inflammatory syndrome in children (MIS-C) and Kawasaki disease (KD) have overlapping clinical features. We compared demographics, clinical presentation, management, and outcomes of patients according to evidence of previous SARS-CoV-2 infection.

METHODS

The International Kawasaki Disease Registry (IKDR) enrolled KD and MIS-C patients from sites in North, Central, and South America, Europe, Asia, and the Middle East. Evidence of previous infection was defined as: Positive (household contact or positive polymerase chain reaction [PCR]/serology), Possible (suggestive clinical features of MIS-C and/or KD with negative PCR or serology but not both), Negative (negative PCR and serology and no known exposure), and Unknown (incomplete testing and no known exposure).

RESULTS

Of 2345 enrolled patients SARS-CoV-2 status was Positive for 1541 (66%) patients, Possible for 89 (4%), Negative for 404 (17%) and Unknown for 311 (13%). Clinical outcomes varied significantly among the groups, with more patients in the Positive/Possible groups presenting with shock, having admission to intensive care, receiving inotropic support, and having longer hospital stays. Regarding cardiac abnormalities, patients in the Positive/Possible groups had a higher prevalence of left ventricular dysfunction, and patients in the Negative and Unknown groups had more severe coronary artery abnormalities.

CONCLUSIONS

There appears to be a spectrum of clinical features from MIS-C to KD with a great deal of heterogeneity, and one primary differentiating factor is evidence for previous acute SARS-CoV-2 infection/exposure. SARS-CoV-2 Positive/Possible patients had more severe presentations and required more intensive management, with a greater likelihood of ventricular dysfunction but less severe coronary artery adverse outcomes, in keeping with MIS-C.

Respiratory pathogen trends in patients with Kawasaki disease during the COVID-19 pandemic and respiratory syncytial virus epidemic in Japan

BACKGROUND

Although the etiology of Kawasaki disease (KD) remains unknown, the most common view is that an infectious agent triggers the activation of the inflammatory cascade in predisposed children. The coronavirus disease 2019 (COVID-19) pandemic has led to the establishment of infection control measures, which reduced the overall incidence of respiratory infections; however, a resurgence of respiratory syncytial virus (RSV) infection occurred in the summer of 2021. This study aimed to examine the relationship between respiratory pathogens and KD during the COVID-19 pandemic and the RSV epidemic in Japan between 2020 and 2021.

METHODS

We retrospectively reviewed the medical charts of pediatric patients with KD or respiratory tract infection (RTI) admitted to National Hospital Organization Okayama Medical Center between December 1, 2020, and August 31, 2021. All patients with KD and RTI underwent multiplex polymerase chain reaction testing upon admission. We classified patients with KD into the three subgroups-pathogen-negative, single pathogen-positive, and multi-pathogen-positive-and compared their laboratory data and clinical features.

RESULTS

This study enrolled 48 patients with KD and 269 with RTI. Rhinovirus and enterovirus were the most prevalent pathogens in both patients with KD and RTI (13 [27.1%] and 132 patients [49.1%], respectively). The clinical characteristics of the pathogen-negative KD group and the pathogen-positive KD group at diagnosis were similar; however, the pathogen-negative group tended to receive additional treatment, such as multiple courses of intravenous immunoglobulin, intravenous methylprednisolone, infliximab, cyclosporine A, and plasmapheresis, more frequently. The number of patients with KD remained stable when RTI was not prevalent but increased following the surge in RTI with RSV.

CONCLUSIONS

An epidemic of respiratory infections led to an increase in the incidence of KD. Patients with respiratory pathogen-negative KD could have greater recalcitrance to intravenous immunoglobulin than those with respiratory pathogen-positive KD.

Is Kawasaki Disease Caused by a Respiratory Virus?

BACKGROUND

Kawasaki disease is characterized by high fever, rash, cervical lymphadenopathy, conjunctival injection, oral mucous membrane changes and swelling of the extremities followed by skin sloughing. Despite >50 years of study, no bacterial, viral or other infectious agent has been consistently associated with the illness. The lockdown and social distancing for COVID-19 in March 2020 led to a marked decrease in respiratory virus circulation. This provided an "experiment of nature" to determine whether Kawasaki disease would decline in parallel.

METHODS

Discharge ICD-10 diagnosis codes were obtained from the Vizient Clinical Data Base for Kawasaki disease and respiratory viruses, and analyzed for the age group < 5 years. Weekly respiratory virus positivity data were also obtained from BioFire Diagnostics.

RESULTS

Common enveloped respiratory viruses declined precipitously from April 2020 through March 2021 to levels at or below historical seasonal minimum levels. Kawasaki Disease declined about 40% compared with 2018-2019, which is distinctly different from the pattern seen for the enveloped respiratory viruses. Strong seasonality was seen for Kawasaki disease as far back as 2010, and correlated most closely with respiratory syncytial virus, human metapneumovirus and less so with influenza virus suggesting there is a baseline level of Kawasaki disease activity that is heightened during yearly respiratory virus activity but that remains at a certain level even in the near total absence of respiratory viruses.

CONCLUSIONS

The striking decrease in enveloped respiratory viruses after lockdown and social distancing was not paralleled by a comparable decrease in Kawasaki disease incidence, suggesting a different epidemiology.

Classification and epidemiology of vasculitis: Emerging concepts

The recent publication of the American College of Rheumatology (ACR)-European Alliance of Associations for Rheumatology (EULAR) classification criteria for large vessel vasculitis and anti-neutrophil cytoplasmic antibody (ANCA)-associated vasculitides (AAVs) has provided modern criteria for the classification of these conditions, which incorporate contemporary methods of investigation and diagnosis. Further validation is required in independent cohorts, especially from populations that were not well represented in the development cohort. Studies of the occurrence of large vessel vasculitis report that Takayasu arteritis is a rare disease in most populations, and giant cell arteritis is the most common vasculitis in older populations. The incidence of AAV appears to have plateaued, but the prevalence is increasing as a result of lower mortality. The new classification criteria may affect the reported incidence and prevalence, and studies will be needed to confirm this. The impact of COVID-19 on the occurrence of the vasculitides is not completely known, but there is evidence of reduced occurrence of Kawasaki disease and IgA-associated vasculitis following lockdowns with reduced transmission of possible trigger infectious agents.

Increased frequency of central precocious puberty during the coronavirus disease (COVID-19) pandemic at a single center in the Osaka Metropolitan Area of Japan

As environmental factors are known to affect the timing of puberty, self-isolation during the coronavirus disease (COVID-19) pandemic may affect the incidence of central precocious puberty (CPP). This study aimed to evaluate the frequency of CPP during the COVID-19 pandemic at a single center in the Osaka metropolitan area of Japan. We retrospectively analyzed the annual frequency of CPP occurrence before and after the first declaration of COVID-19 state of emergency in Japan at our hospital. We performed an interrupted time-series analysis to investigate the frequency of patients with CPP at our hospital from 2016 to 2021. There was a significant increase in the frequency of patients with CPP before and after the state of emergency declaration, both overall and among females. However, there was no significant increase in the number of males. There were no significant differences in the clinical, auxological, and endocrinological features between those diagnosed before and after the state of emergency. Overall, the frequency of CPP significantly increased during the COVID-19 pandemic at a single center in the Osaka metropolitan area of Japan.

Evaluation of the association of birth order and group childcare attendance with Kawasaki disease using data from a nationwide longitudinal survey

Background

Kawasaki disease (KD) is a form of pediatric systemic vasculitis. Although the etiology remains unclear, infections have been identified as possible triggers. Children with a later birth order and those who attend childcare are at a higher risk of infections due to exposure to pathogens from their older siblings and other childcare attendees. However, longitudinal studies exploring these associations are limited. Thus, we aimed to elucidate the relationship between birth order, group childcare attendance, and KD, using a nationwide longitudinal survey in Japan.

Methods

In total, 36,885 children born in Japan in 2010 were included. The survey used questionnaires to identify hospitalized cases of KD. We evaluated the relationship between birth order classification, group childcare attendance, and KD prevalence every year, from 6 to 66 months of age. For each outcome, odds ratios (ORs), and 95% confidence intervals (CIs) were estimated after adjusting for child factors, parental factors, and region of residence.

Results

Children with higher birth orders were more likely to be hospitalized with KD at 6-18 months of age (second child OR: 1.77, 95% CI: 1.25-2.51; third child OR: 1.70, 95% CI: 1.08-2.65). This trend was stronger for children who did not attend group childcare (second child OR: 2.51, 95% CI: 1.57-4.01; third child OR: 2.41, 95% CI: 1.30-4.43). An increased risk of KD hospitalization owing to the birth order was not observed in any age group for children in the childcare group.

Conclusions

Children with higher birth orders were at high risk for hospitalization due to KD at 6-18 months of age. The effect of birth order was more prominent among the children who did not attend group childcare.

Epidemiological and Clinical Features of Kawasaki Disease During the COVID-19 Pandemic in the United States

IMPORTANCE

Public health measures implemented during the COVID-19 pandemic had widespread effects on population behaviors, transmission of infectious diseases, and exposures to environmental pollutants. This provided an opportunity to study how these factors potentially influenced the incidence of Kawasaki disease (KD), a self-limited pediatric vasculitis of unknown etiology.

OBJECTIVES

To examine the change in KD incidence across the United States and evaluate whether public health measures affected the prevalence of KD.

DESIGN, SETTING, AND PARTICIPANTS

This multicenter cohort study included consecutive, unselected patients with KD who were diagnosed between January 1, 2018, and December 31, 2020 (multicenter cohort with 28 pediatric centers), and a detailed analysis of patients with KD who were diagnosed between January 1, 2002, and November 15, 2021 (Rady Children's Hospital San Diego [RCHSD]).

MAIN OUTCOMES AND MEASURES

For the multicenter cohort, the date of fever onset for each patient with KD was collected. For RCHSD, detailed demographic and clinical data as well as publicly available, anonymized mobile phone data and median household income by census block group were collected. The study hypothesis was that public health measures undertaken during the pandemic would reduce exposure to the airborne trigger(s) of KD and that communities with high shelter-in-place compliance would experience the greatest decrease in KD incidence.

RESULTS

A total of 2461 KD cases were included in the multicenter study (2018: 894; 2019: 905; 2020: 646), and 1461 cases (median [IQR] age, 2.8 years [1.4-4.9 years]; 900 [61.6%] males; 220 [15.1%] Asian, 512 [35.0%] Hispanic, and 338 [23.1%] White children) from RCHSD between 2002 and 2021 were also included. The 28.2% decline in KD cases nationally during 2020 (646 cases) compared with 2018 (894 cases) and 2019 (905 cases) was uneven across the United States. For RCHSD, there was a disproportionate decline in KD cases in 2020 to 2021 compared with the mean (SD) number of cases in earlier years for children aged 1 to 5 years (22 vs 44.9 [9.9]; P = .02), male children (21 vs 47.6 [10.0]; P = .01), and Asian children (4 vs 11.8 [4.4]; P = .046). Mobility data did not suggest that shelter-in-place measures were associated with the number of KD cases. Clinical features including strawberry tongue, enlarged cervical lymph node, and subacute periungual desquamation were decreased during 2020 compared with the baseline period (strawberry tongue: 39% vs 63%; P = .04; enlarged lymph node: 21% vs 32%; P = .09; periungual desquamation: 47% vs 58%; P = .16). School closures, masking mandates, decreased ambient pollution, and decreased circulation of respiratory viruses all overlapped to different extents with the period of decreased KD cases. KD in San Diego rebounded in the spring of 2021, coincident with lifting of mask mandates.

CONCLUSIONS AND RELEVANCE

In this study of epidemiological and clinical features of KD during the COVID-19 pandemic in the United States, KD cases fell and remained low during the period of masking and school closure. Mobility data indicated that differential intensity of sheltering in place was not associated with KD incidence. These findings suggest that social behavior is associated with exposure to the agent(s) that trigger KD and are consistent with a respiratory portal of entry for the agent(s).

Changes in the Clinical Characteristics of Kawasaki Disease After Coronavirus Disease (COVID-19) Pandemic: A Database Analysis

BACKGROUND

The impact of the coronavirus disease 2019 (COVID-19) pandemic on Kawasaki disease (KD) has not yet been established. We investigated changes in the observed number and severity of KD cases and accompanying coronary artery complications during the COVID-19 pandemic in Korea.

METHODS

This retrospective observational study included patients aged < 18 years with acute-phase KD diagnosed between March 2018 and February 2021. Data were extracted from the Clinical Data Warehouse that houses data from five affiliated university hospitals in Korea. We analyzed changes in the number of patient admissions and clinical characteristics, including cardiac complications, before and after the onset of the COVID-19 pandemic.

RESULTS

A total of 475 admissions were included in the analysis. After March 2020, we observed a significant decrease of 33% in the number of hospitalizations for KD compared with the average number of hospitalizations during the previous 2 years. The number of admissions per month significantly decreased by 7.9 persons/month (95% confidence interval, -13.8 to -2.0; P < 0.05) compared with that before COVID-19. By contrast, the proportion of patients aged < 1 year with KD increased. The proportion of patients with refractory KD and the rate of cardiac complications did not change significantly.

CONCLUSION

Since the onset of the COVID-19 pandemic, the total number of hospital admissions for KD has decreased in Korea. Although the proportion of admissions of infants aged < 1 year increased, no changes were observed in clinical courses and complications.

Number of Kawasaki Disease Admissions Is Associated with Number of Domestic COVID-19 and Severe Enterovirus Case Numbers in Taiwan

Background: Non-pharmaceutical interventions (NPIs) introduced in response to the COVID-19 pandemic, including mask-wearing and social distancing, have changed the prevalence of circulating viruses in the community. Since viral infections represent a potential triggering factor for the development of Kawasaki disease (KD), we examined the relationship between KD admission rates and the number of COVID-19, severe influenza, and severe enterovirus infections both before and after the COVID-19 pandemic. Methods: We conducted a retrospective study using data obtained from the Chang Gung Research Database (including seven Taiwanese hospitals and more than 10,000 beds) and the Centers for Disease Control in Taiwan from January 2018 to December 2020. We recorded the number of KD admissions, as well as COVID-19, severe influenza, and severe enterovirus infections. Results: The numbers of KD admissions, severe enterovirus infections, and severe influenza infections were significantly lower from April to September 2020. The number of KD hospitalizations was positively correlated with the number of domestic COVID-19 cases (p = 0.001). A decrease in KD admission numbers was positively correlated with a decrease in severe enterovirus case numbers (p = 0.007). Conclusion: Our findings provide further evidence that viral infections may be an important trigger factor in the development of KD. Therefore, NPIs may not only prevent transmissible viral infections in children, but also decrease the risk of KD.

Decreased number of inpatients with community-acquired pneumonia during the COVID-19 pandemic: A large multicenter study in Japan

The COVID-19 pandemic has shaped the dynamics of many diseases. This study aims to assess how the pandemic affected community-acquired pneumonia admission of all age groups among Japanese hospitals with various size and availability of COVID-19 wards. Our findings revealed a 44%–53% reduction in community-acquired pneumonia admission among 82 hospitals in Japan, from April through September of 2020, compared to the same period of 2019. Decreases were consistently found among hospitals with and without COVID-19 wards. The most significant decrease was found in the age group <20 years old. COVID-19 preventive measures and personal hygiene are considered to be effective measures to prevent the spreading of this disease. As vaccination progresses and the public gradually become less attentive to infection countermeasures, incidence of community-acquired pneumonia may increase in the coming season. Continued monitoring is required.

Decline in pediatric admission on an isolated island in the COVID-19 pandemic

BACKGROUND

A decrease in pediatric hospitalizations during the COVID-19 pandemic has been reported worldwide; however, few studies have examined areas with a limited number of COVID-19 cases, where influenced by viral interference by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) is minimum.

METHODS

We conducted an epidemiological study of pediatric hospitalizations on Sado, an isolated island in Niigata, Japan, that was unique environment with few COVID-19 cases and reliable pediatric admissions monitoring. We compared numbers of monthly hospitalizations and associated diagnoses for the periods April 2016 to March 2020 (pre-pandemic period) and April 2020 to March 2021 (pandemic period).

RESULTS

Data were analyzed for 1,144 and 128 patients in the pre-pandemic and pandemic periods, respectively. We observed only three adults and no pediatric COVID-19 cases during the pandemic period. The number of monthly admissions was significantly lower in the pandemic period (median [interquartile ranges (IQR)]: 11.0 [7.0-14.0]) than in the pre-pandemic period (23.0 [20.8-28.3]; P < 0.001). Similar decreases were observed for hospitalizations due to respiratory tract infection (P < 0.01), but not for asthma exacerbation (P = 0.15), and gastrointestinal tract infection (P = 0.33).

CONCLUSIONS

Pediatric hospitalizations during the pandemic significantly decreased on an isolated Japanese island where COVID-19 was not endemic and all pediatric admissions were ascertainable. This observation highlights the impact of decreased travel and increased awareness of infection control measures on pediatric hospitalizations due to infectious diseases, not by the SARS-CoV-2 viral interference.

Spatiotemporal clusters of Kawasaki disease in South Korea from 2008 to 2017: A municipal-level ecological study

INTRODUCTION

As the etiology of Kawasaki disease (KD) remains unknown, identifying spatiotemporal clusters with proper stratification of KD could provide further evidence for investigating the triggers of KD. However, spatiotemporal distributions of KD with sex stratification have never been reported. Therefore, we aimed to analyze the spatiotemporal patterns of KD by sex in South Korea.

METHODS

We extracted epidemiologic week (Epiweek)-based KD cases in patients <5 years of age (ICD-10-CM code: M303) from 2008 to 2017 national health insurance service data at the 250 municipal level. To determine whether spatial autocorrelation and persistent municipal-level clusters exist, year- and sex-stratified global Moran's I statistics, Getis-Ord Gi* statistics, and emerging hotspot analysis on KD incidence were conducted.

RESULTS

A total of 72,510 KD cases were reported between 2008 and 2017 (male-to-female ratio = 1.40:1). Incidence has increased since 2008, with the highest incidence in 2016 (396.8 per 100,000 population). KD had seasonality of winter and summer but different by sex. Positive spatial autocorrelation was consistently reported in every stratum, with the 2011-2014 period having the strongest index value (total sex I = 0.286, p < 0.001; male I = 0.242, p < 0.001; female I = 0.213, p < 0.001). Hot spots were consistently detected in the northern parts, and cold spots were in the southern part for 9 years in both sexes. The emerging hot spot analysis showed new, consecutive, and sporadic hot spots on the northwestern and eastern coasts and new and sporadic cold spots in the southwestern part. However, the distribution and proportion of hot or cold spot types differed according to sex.

DISCUSSION

The spatiotemporal features of KD had limits to concluding that only infectious triggers result in KD occurrence. Therefore, our findings support the notion that KD is a syndrome with multiple factors, including infectious, genetic, and environmental factors, that are associated with sex differences.

Kawasaki disease following SARS-CoV-2 infection: Stronger inflammation with no increase in cardiac complications

BACKGROUND

Herein we investigate the difference between Kawasaki disease (KD) with and without a recent history of SARS-CoV-2 infection.

METHODS

We compared the clinical characteristics of patients with KD during the SARS-CoV-2 pandemic in a single children's hospital in Korea. Fifty-two patients were enrolled and divided into group 1 (with a history of COVID-19, n = 26) and group 2 (without a history of COVID-19, n = 26) according to whether or not they contracted COVID-19 within the 8 weeks before hospitalization. Data, including clinical features and laboratory results, were analyzed and compared between groups.

RESULTS

The median age of patients was significantly higher in group 1 than in group 2 (53 months [IQR, 24-81] vs. 15 months [IQR, 6-33], p = 0.001). The incidence of cervical lymphadenopathy was significantly higher (p = 0.017), while that of BCGitis was significantly lower in group 1 (p = 0.023), and patients had a significantly longer hospital stay (5 days [IQR, 3-8] vs. 3 days [IQR, 3-4], p = 0.008). In group 1, platelet count was significantly lower (p = 0.006), and hemoglobin and ferritin levels were significantly higher (p = 0.013 and p = 0.001, respectively) on the first admission day. Following treatment with intravenous immunoglobulin (IVIG), the platelet count was significantly lower (p = 0.015), and the percentage of neutrophils and neutrophil-to-lymphocyte ratio were significantly higher in group 1 (p = 0.037 and p = 0.012). Although there was no statistical difference, patients requiring infliximab treatment due to prolonged fever was only in group 1. The incidence of cardiovascular complications did not differ between the groups.

CONCLUSIONS

Post-COVID KD showed a stronger inflammatory response than KD-alone, with no differences in cardiac complications.

Global epidemiology of vasculitis

The many forms of vasculitis are characterized by inflammation of blood vessels, leading to potentially long-term sequelae including vision loss, aneurysm formation and kidney failure. Accurate estimation of the incidence and prevalence has been hampered by the absence of reliable diagnostic criteria and the rarity of these conditions; however, much progress has been made over the past two decades, although data are still lacking from many parts of the world including the Indian subcontinent, China, Africa and South America. Giant cell arteritis occurs in those aged 50 years and over and seems to mainly affect persons of northern European ancestry, whereas Takayasu arteritis occurs mainly in those aged under 40 years. By contrast, Kawasaki disease mainly occurs in children aged under 5 years and is most common in children of Asian ancestry, and IgA vasculitis occurs in children and adolescents. Although much less common than giant cell arteritis, the different forms of antineutrophil cytoplasmic antibody-associated vasculitis are being increasingly recognized in most populations and occur more frequently with increasing age. Behçet syndrome occurs most commonly along the ancient silk road between Europe and China. Much work needs to be done to better understand the influence of ethnicity, geographical location, environment and social factors on the development of vasculitis.

Multi-inflammatory syndrome and Kawasaki disease in children during the COVID-19 pandemic: A nationwide register-based study and time series analysis

Aim

We investigated whether the ongoing COVID‐19 pandemic was associated with the occurrence of Kawasaki disease or with multi‐inflammatory syndrome in children (MIS‐C).

Methods

This national Finnish register‐based study was based on laboratory‐confirmed severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infections, MIS‐C and Kawasaki disease cases. We performed a time series analysis on the occurrence of Kawasaki disease in 2016–2020.

Results

In 2020, there were 5170 laboratory‐confirmed COVID‐19 cases in children under 18 years of age and five fulfilled the MIS‐C case definition. The occurrence of MIS‐C was 0.97 per 1000 (95% confidence interval: 0.31‐2.26) laboratory‐confirmed SARS‐CoV‐2 infections in children. Our time series analysis showed that Kawasaki disease cases decreased during the COVID‐19 pandemic. The seasonally adjusted incidence rate ratio was 0.49 (95% confidence interval: 0.32‐0.74) when it was compared to pre‐pandemic levels. This coincided with a reduced occurrence of respiratory infections, due to social distancing in the population.

Conclusion

This nationwide register‐based study found that MIS‐C was a rare complication of the SARS‐CoV‐2 infection. The occurrence of Kawasaki disease and respiratory infections decreased during the pandemic. This suggests that transmissible microbes may play an important role in Kawasaki disease and social distancing may have a protective effect.

Kawasaki Disease Hospitalizations in the United States 2016-2020: A Comparison of Before and During the Coronavirus Disease 2019 Era

BACKGROUND

Kawasaki disease (KD) is an acute vasculitis of young children. A comparison of US hospitalization rates and epidemiologic features of KD in 2020 to those of precoronavirus disease years has yet to be reported.

METHODS

Using a large, inpatient database, we conducted a retrospective cohort study and analyzed data for patients with (1) diagnosis coding for KD, (2) IV immunoglobulin treatment administered during hospitalization and (3) discharge date between January 1, 2016, and December 30, 2020. Severe cases were defined as those requiring adjunctive therapy or IV immunoglobulin-resistant therapy.

RESULTS

The annual number of KD hospitalizations were stable from 2016 to 2019 (n = 1652, 1796, 1748, 1692, respectively) but decreased in 2020 (n = 1383). KD hospitalizations demonstrated seasonal variation with an annual peak between December and April. A second peak of KD admissions was observed in May 2020. The proportion of KD cases classified as severe increased to 40% in 2020 from 33% during the years 2016-2019 (P < 0.01). Median age in years increased from 2.9 in subjects hospitalized from 2016 to 2019 to 3.2 in 2020 (P = 0.002).

CONCLUSIONS

Compared with the previous 4 years, the annual number of pediatric KD admissions decreased, and children discharged with diagnostic codes for KD in 2020 were generally older and more likely to have severe morbidity possibly reflective of misdiagnosed multisystem inflammatory syndrome in children. Clinicians should be wary of a possible rise in KD rates in the postcoronavirus disease 2019 era as social distancing policies are lifted and other viruses associated with KD return.

Impact of Social Distancing on Kawasaki Disease-associated Hospitalization, South Korea

We conducted a cohort study to estimate the impact of social distancing on incidence of Kawasaki disease (KD) in Korean children, using the nationally representative data. The KD-related hospitalization rate has declined significantly from -38.8% (April) to 81.7% (June). The decrease in diagnosis of KD adds clue for infectious etiology of KD and the establishment of preventive measures.