Acute and Postacute Clinical Characteristics of Coronavirus Disease 2019 in Children in Japan

Nationwide epidemiology and health resource use among children with COVID-19 in Japan

BACKGROUND

The COVID-19 pandemic posed substantial challenges to healthcare systems. Understanding the responses of pediatric health services is crucial for future pandemic planning and preparedness, yet such data remains limited.

METHODS

In this retrospective cohort study, we analyzed data from administrative databases developed by Japan Medical Data Center and DeSC Healthcare Inc. The dataset comprised records of 2,612,511 children, totaling 60,224,888 person-months, from January 2020 to May 2022. Multivariate generalized estimation equations were used to examine the incidence rates of COVID-19 and associated health resource use.

RESULTS

Our analysis revealed that the incidence rates of COVID-19 gradually increased from Wave I (2.2 cases per 100,000 person-months) to Wave V (177.8cases per 100,000 person-months), with a notable elevation during Wave VI (2367.7 cases per 100,000 person-months). While nucleic acid amplification tests were primarily used during Waves I-V, the use of rapid antigen tests markedly increased in Wave VI. The hospitalization rates increased gradually from 0.2 in Wave I to 10.2 events per 100,000 person-months in Wave VI, and the case-hospitalization risk decreased from 14.9% in Wave II to 0.7% in Wave VI. Additionally, we observed decreasing trends in the use of antibiotics (Wave I, 31.8%; Wave VI, 9.0%), whereas antipyretic use rose from Wave I (56.1%) to Wave VI (86.6%).

CONCLUSIONS

Our study highlighted essential changes in the nationwide pediatric healthcare system's response to the COVID-19 pandemic. These findings provide valuable insights into the future pandemic planning and preparedness.

Navigating the Spectrum of Two Pediatric COVID-19 Complications: Multi-System Inflammatory Syndrome in Children and Post-Acute Sequelae of SARS-CoV-2 Infection

PURPOSE

This review summarizes the current scope of understanding associated with two common post-infectious complications associated with COVID-19 infection: Multi-System Inflammatory Syndrome in Children (MIS-C) and Post-Acute Sequelae of SARS-CoV-2 infection (PASC). It identifies current gaps in the knowledge and issues that may limit the ability to fill these gaps. This review provides a framework to drive continued research.

METHODS

A comprehensive review of the current literature was performed, identifying seminal articles describing the emergence of MIS-C and PASC, and works from the literature focused on the clinical implications and pathophysiologic understanding of these disorders.

FINDINGS

Although pediatric patients experienced few severe cases of acute COVID-19 infection, the burden of disease from post-infectious sequelae is substantial. Mortality is low, but morbidity is significant. There are still numerous unknowns about the pathophysiology of both MIS-C and PASC; however, with widespread immunity developing after increased vaccination and prior infection, it may be difficult to perform adequate prospective studies to answer pathophysiologic questions. Long-term sequalae of MIS-C seem to be minimal whereas, by definition, PASC is an ongoing problem and may be severe.

IMPLICATIONS

The rapid sharing of information regarding novel conditions such as MIS-C and PASC are key to interventions related to future post-infectious sequelae outside of those stemming from COVID-19. Although MIS-C seems unlikely to return as a clinical condition in substantial numbers, there is still significant learning that can be gleaned from existing patients about general aspects of epidemiology, equity, and pathophysiology. There is significant morbidity associated with PASC and additional resources need to be dedicated to determining appropriate and effective therapies moving forward.

Clinical Practice Patterns, Health Resource Use and Risk Factors for Severe Conditions Among Children Hospitalized With COVID-19 in Japan

BACKGROUND

The trends in clinical practice patterns and health resource use, as well as risk factors for severe conditions among children hospitalized with coronavirus disease-2019 (COVID-19), remain unclear.

MATERIALS AND METHODS

We conducted a retrospective observational study consisting of 9876 children hospitalized with COVID-19 during 2020-2022 using the Medical Data Vision database in Japan. We investigated trends in patient characteristics, health resource use, treatment patterns and laboratory data. Additionally, log-binomial regression models were used to investigate the risk factors associated with severe COVID-19 among pediatric inpatients with COVID-19.

RESULTS

We observed decreasing trends in the lengths of hospital stays, healthcare costs, computed tomography use, and antibiotic use, and increasing trends in treatment with intravenous hydration and use of antipyretics, antiepileptics, antiemetics and antivirals from the first wave to the seventh wave of COVID-19 pandemic. During the 3-year period, the risk of severe COVID-19 was almost stable at 3%. Risk factors associated with severe COVID-19 were children less than 1 year old [risk ratio (RR): 1.69; 95% confidence interval (CI): 1.02-2.78], the number of complex chronic diseases (RR for 1 disease: 4.49; 95% CI: 2.76-7.32; RR for 2 or more diseases: 10.2; 95% CI: 5.19-20.3) and asthma (RR: 1.84; 95% CI: 1.06-3.20).

CONCLUSIONS

Our study observed the changes in practice patterns and health resource use for children hospitalized with COVID-19 and identified risk factors associated with severe COVID-19. These findings indicate the importance of vigilant monitoring and tailored treatment strategies in children with these risk factors.

SARS-CoV-2 nucleocapsid antigen in plasma of children hospitalized for COVID-19 or with incidental detection of SARS-CoV-2 infection

In hospitalized children, SARS-CoV-2 infection can present as either a primary reason for admission (patients admitted for COVID-19) or an incidental finding during follow-up (patients admitted with COVID-19). We conducted a nested case-control study within a cohort of pediatric patients with confirmed SARS-CoV-2 infection, to investigate the concentration of plasma nucleocapsid antigen (N-Ag) in children admitted for COVID-19 or with COVID-19. While reverse transcriptase polymerase chain reaction Ct values in nasopharyngeal swab were similar between the two groups, children admitted for COVID-19 had a higher rate of detectable N-Ag (12/18 (60.7%) versus 6/18 (33.3%), p = 0.0455) and a higher concentration of N-Ag (medians: 19.51 g/mL vs. 1.08 pg/mL, p = 0.0105). In children hospitalized for COVID-19, the youngest had higher concentration of N-Ag (r = -0.74, p = 0.0004). We also observed a lower prevalence of detectable spike antibodies in children hospitalized for COVID-19 compared to those hospitalized for other medical reasons (3/15 [20%] vs. 13/16 [81.25%], respectively, p = < 0.0011), but similar rates of IgG nucleocapsid antibodies (5/14 [35.7%] vs. 6/17 [35.3%], respectively, p = 0.99). Our findings indicate that N-Ag is associated with COVID-19-related hospitalizations in pediatric patients, and less frequently detected in children tested positive for SARS-CoV-2 but hospitalized for another medical reason. Further studies are needed to confirm the value of N-Ag in identifying COVID-19 disease infections in which SARS-CoV-2 is the main pathogen responsible for symptoms.

Febrile seizure in children with COVID-19 during the Omicron variant-predominant era: A single-center study

OBJECTIVE

Coronavirus disease 2019 (COVID-19) has significantly impacted medical services worldwide. During the Omicron variant-predominant era, febrile seizure (FS) in patients with COVID-19 increased compared to that in the pre-Omicron variant era. Therefore, this study aimed to demonstrate the clinical characteristics of FS in patients with COVID-19.

METHODS

We surveyed patients aged < 16 years who presented with FS to the emergency room of Tottori University Hospital. The patients were divided into two groups: FS patients with COVID-19 (FS with COVID-19 group) and FS patients without COVID-19 (FS without COVID-19 group) as per the results of the respiratory multiplex array test. Patients with positive results for both SARS-CoV-2 and other microorganisms were excluded. We obtained data on the patients' clinical backgrounds, symptoms, seizure duration, type of FS (simple or complex), diagnostic examinations, laboratory test results, and treatment. We compared the data between the FS with and without COVID-19 groups.

RESULT

A total of 128 patients with FS met the inclusion criteria. Of these, 18 patients and 110 patients were included in the FS with COVID-19 group and without COVID-19 group, respectively. The late FS onset (>60 months) were significantly more common in the FS with COVID-19 group than that in the FS without COVID-19 group. Moreover, patients in the FS with COVID-19 group had significantly longer seizure durations than those in the FS without COVID-19 group. A diazepam (DZP) suppository was administered to 72% of FS patients with COVID-19 after the first seizure during a febrile episode.

CONCLUSION

FS patients with COVID-19 had different distributions of age at onset and seizure duration than those without COVID-19. The use of DZP suppositories was more frequent in FS patients with COVID-19 compared to those without COVID-19.

Differences in Clinical Presentation of COVID-19 in Children Hospitalized During Domination of Early (BA.1, BA.2) and Late (BA.5, BA.2.75, BQ.1 and XBB.1.5) SARS-CoV-2 Omicron Subvariants

This study analyzed data for 1098 children: 575 diagnosed with COVID-19 between January and June 2022 (early Omicron) and 523 hospitalized from July 2022 to April 2023 (late Omicron). New Omicron subvariants lead to similar recovery rates without deaths and acute respiratory distress syndrome in children as BA.1 and BA.2, however, they more often cause fever and croup. Children suffering from comorbidities, presenting with pulmonary lesions and older, may be prone to a more severe consequences of COVID-19 in terms of the currently dominating Omicron subvariants.

Long COVID in children and adolescents: prevalence, clinical manifestations, and management strategies

Long coronavirus disease (COVID), also known as postacute sequelae of severe acute respiratory syndrome coronavirus 2 infection, has been defined as signs and symptoms which persist for 4 weeks or even lasting for 6 months after the initial infection. Although the prevalence of long COVID in children is currently unknown, epidemiological investigations have reported cases in pediatric populations. Clinical manifestations of long COVID in children include respiratory symptoms, such as cough and dyspnea, as well as neuropsychiatric and general conditions, including fatigue, headache, and muscle weakness. The pathophysiology of long COVID in children is still being investigated, but potential mechanisms include viral persistence, autoimmunity, and neuroinflammation. Risk factors for long COVID in children are not yet well understood, but studies have suggested that children with a history of severe acute COVID-19 infection or comorbidities may be at increased risk. Evaluation for respiratory symptoms of long COVID in children is essential, including spirometry and imaging studies to assess lung function and any potential damage. Furthermore, long COVID in children has been associated with a higher prevalence of mental health problems than in adults, emphasizing the importance of monitoring and addressing these aspects in pediatric patients. Although our understanding of long COVID in children and adolescents is still evolving, it is clear that the condition can have significant impacts on their health and well-being. The aim of this review is to synthesize the current knowledge on the prevalence, risk factors, and pathophysiology of long COVID in children and adolescents, and to discuss potential management strategies based on existing evidence.

Factors affecting guardians' decision-making regarding the SARS-CoV-2 vaccine

BACKGROUND

In Japan, the vaccination rate against the SARS-CoV-2 vaccine for children was low. Therefore, in this study we investigated the factors influencing guardians' decision-making regarding vaccination of their children.

METHODS

From November 1, 2022 to March 31, 2023, pediatric clinics, departments, and midwifery clinics in Saitama Prefecture requested guardians of children under the age of 15 to complete an online questionnaire.

RESULTS

Responses were obtained from 894 guardians of children aged 6 months to 15 years; 142 had had one of their children vaccinated at least once and 629 had not had any of their children vaccinated. Among guardians who had not had any of their children vaccinated, "the Age of children" was significantly younger (p < 0.001) and "Prevalence" (p < 0.001), "Free vaccination" (p < 0.001), and "Intentions of national and local governments" (p = 0.005) were selected as reasons significantly less frequently in comparison to guardians who had vaccinated their children. "Japanese adverse reactions" (p < 0.001), "Japanese effectiveness" (p < 0.001), "Adverse reactions" (p < 0.001), "History of adverse reactions" (p < 0.001), and "Reputation of friends" (p = 0.006) were selected significantly more frequently by guardians who had not had any of their children vaccinated.

CONCLUSIONS

Guardians who had had one of their children vaccinated at least once emphasized the importance of prevalence and free vaccination. On the other hand, guardians who had not had any of their children vaccinated placed particular importance on adverse reactions and the Japanese data on effectiveness. To guide the decision-making of guardians, it is necessary to quickly collect and publish data on adverse reactions and effectiveness, particularly in Japanese individuals, so that citizens can decide whether to vaccinate themselves and their children.

Adverse reactions in young children receiving the coronavirus disease 2019 vaccine

BACKGROUND

We sought to investigate the occurrence of adverse reactions in Japanese children aged 6 months to 4 years who received the BNT162b2 coronavirus disease 2019 (COVID-19) vaccine, to examine parental considerations, and to evaluate potential risk factors associated with post-vaccination fever.

METHODS

This cross-sectional survey study targeted 1617 children aged 6 months to 4 years who received their primary doses of BNT162b2 from November 10, 2022, to April 30, 2023, in Okayama Prefecture. We surveyed the occurrence of local and systemic reactions within 1 week after vaccination, and described the incidence proportions of adverse reactions for 515 participants overall and by age group. The study also examined the impact of previous COVID-19 infection and co-administration of the seasonal influenza vaccine on post-vaccination fever. A survey also assessed parents' reasons for vaccinating their children and the sources of information they used.

RESULTS

Adverse reactions were infrequent (5.2%, with fever ≥37.5°C; no cases exceeded 39°C) and did not increase with vaccine doses administered. The risk of post-vaccination fever was not statistically associated with a history of COVID-19-the adjusted risk ratio (aRR) was 0.99, and the 95% confidence interval (CI) was 0.41-2.39-but was associated with co-administration of the seasonal influenza vaccine (aRR 3.24, 95% CI 1.14-9.18). Parental decisions regarding vaccination were influenced by official government guidelines and primary care physicians' opinion.

CONCLUSION

This study provides valuable insight into the safety profile of the BNT162b2 vaccine in Japanese children aged 6 months to 4 years. Further research involving larger cohorts and appropriate control groups is needed.