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

BACKGROUND: The clinical features of coronavirus disease 2019 (COVID-19) in children have been changing because of the emergence and rapid spread of variants of concern (VOC). The increase in cases infected with VOC has brought concern with persistent symptoms after COVID-19 in children. This survey aimed to analyze the clinical manifestations and persistent symptoms of pediatric COVID-19 cases in Japan. METHODS: We analyzed the clinical manifestations of pediatric COVID-19 cases reported between February 2020 and April 2022 in Japan, using a dedicated database updated voluntarily by the members of the Japan Pediatric Society. Using the same database, we also analyzed persistent symptoms after COVID-19 in children who were diagnosed between February 2020 and November 2021. RESULTS: A total of 5411 and 1697 pediatric COVID-19 cases were included for analyzing clinical manifestations and persistent symptoms, respectively. During the Omicron variant predominant period, the percentage of patients with seizures increased to 13.4% and 7.4% in patient groups 1-4 and 5-11 years of age, respectively, compared with the pre-Delta (1.3%, 0.4%) or Delta period (3.1%, 0.0%). Persistent and present symptoms after 28 days of COVID-19 onset were reported in 55 (3.2%). CONCLUSIONS: Our survey showed that the rate of symptomatic pediatric COVID-19 cases increased gradually, especially during the Omicron variant predominant period, and a certain percentage of pediatric cases had persistent symptoms. Certain percentages of pediatric COVID-19 patients had severe complications or prolonged symptoms. Further studies are needed to follow such patients.

The clinical characteristics of pediatric coronavirus disease 2019 in 2020 in Japan.

BACKGROUND: The COVID-19 pandemic has affected the lives of people of all ages. Most reports on pediatric cases suggest that children experience fewer and milder symptoms than do adults. This is the first nationwide study in Japan focusing on pediatric cases reported by pediatricians, including cases with no or mild symptoms. METHODS: We analyzed the epidemiological and clinical characteristics and transmission patterns of 840 pediatric (<16 years old) COVID-19 cases reported between February and December 2020 in Japan, using a dedicated database which was maintained voluntarily by members of the Japan Pediatric Society. RESULTS: Almost half of the patients (47.7%) were asymptomatic, while most of the others presented mild symptoms. At the time of admission or first outpatient clinic visit, 84.0% of the cases were afebrile (<37.5°C). In total, 609 cases (72.5%) were exposed to COVID-19-positive household members. We analyzed the influence of nationwide school closures that were introduced in March 2020 on COVID-19 transmission routes among children in Japan. Transmission within households occurred most frequently, with no significant difference between the periods before and after declaring nationwide school closures (70.9% and 74.5%, respectively). CONCLUSIONS: COVID-19 symptoms in children are less severe than those in adults. School closure appeared to have a limited effect on transmission. Controlling household transmission from adult family members is the most important measure for prevention of COVID-19 among children.

Anti-high mobility group box 1 monoclonal antibody suppressed hyper-permeability and cytokine production in human pulmonary endothelial cells infected with influenza A virus.

OBJECTIVE: High mobility group box-1 (HMGB1) has been reported to be involved in influenza A virus-induced acute respiratory distress syndrome (ARDS). We studied the efficacy of an anti-HMGB1 mAb using an in vitro model of TNF-α stimulation or influenza A virus infection in human pulmonary microvascular endothelial cells (HMVECs). METHODS: Vascular permeability of HMVECs was quantified using the Boyden chamber assay under tumor necrosis factor-α (TNF-α) stimulation or influenza A virus infection in the presence of anti-HMGB1 mAb or control mAb. The intracellular localization of HMGB1 was assessed by immunostaining. Extracellular cytokine concentrations and intracellular viral mRNA expression were quantified by the enzyme-linked immunosorbent assay and quantitative reverse transcription PCR, respectively. RESULTS: Vascular permeability was increased by TNF-α stimulation or influenza A infection; HMVECs became elongated and the intercellular gaps were extended. Anti-HMGB1 mAb suppressed both the increase in permeability and the cell morphology changes. Translocation of HMGB1 to the cytoplasm was observed in the non-infected cells. Although anti-HMGB1 mAb did not suppress viral replication, it did suppress cytokine production in HMVECs. CONCLUSION: Anti-HMGB1 mAb might be an effective therapy for severe influenza ARDS.

Therapeutic potential of ciclesonide inahalation for COVID-19 pneumonia: Report of three cases.

No specific and effective anti-viral treatment has been approved for COVID-19 so far. Systemic corticosteroid has been sometimes administered to severe infectious diseases combined with the specific treatment. However, as lack of the specific anti-SARS-CoV-2 drug, systemic steroid treatment has not been recommended for COVID-19. We report here three cases of the COVID-19 pneumonia successfully treated with ciclesonide inhalation. Rationale of the treatment is to mitigate the local inflammation with inhaled steroid that stays in the lung and to inhibit proliferation of the virus by antiviral activity. Larger and further studies are warranted to confirm the result of these cases.

Nationwide survey of influenza-associated acute encephalopathy in Japanese adults.

BACKGROUND: Knowledge of adult patients with influenza-associated acute encephalopathy (IAE) is limited. We conducted a detailed survey to investigate the prevalence, clinical features, associated outcomes, and prognostic factors in adult IAE patients. METHOD: A nationwide questionnaire on IAE patients was sent to the departments of Internal Medicine, Neurology, Neurosurgery, and Emergency and Critical Care at all hospitals with ≥200 beds in Japan. RESULTS: 118 patients were diagnosed with IAE during the 2013/14 to 2015/16 influenza seasons, and the estimated annual incidence of IAE in Japanese adults was 0.98/1000,000 population. 44 patients were subsequently enrolled in the detailed study. 93% of patients exhibited disturbance of consciousness. Convulsions and delirious behavior were present in 26% and 40% of patients, respectively. 65% of patients received pulse corticosteroid therapy with methylprednisolone and 21% of patients received intravenous gamma-globulin therapy. 63% of patients achieved a good recovery, but 7% died. Multiple logistic regression analysis revealed that plasma glucose level demonstrated a statistically significant association with poor outcome. CONCLUSION: This nationwide survey provided data for the annual incidence and clinical features of IAE in Japanese adults. Hyperglycemia was indicated as an independent predictor of poor prognosis in IAE patients and reflected systemic hypercytokinemia in IAE pathogenesis.

Corrigendum to "Serum Procalcitonin Levels in Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion".

[This corrects the article DOI: 10.1155/2018/2380179.].

Combined effect of anti-high-mobility group box-1 monoclonal antibody and peramivir against influenza A virus-induced pneumonia in mice.

Human pandemic H1N1 2009 influenza virus causes significant morbidity and mortality with severe acute lung injury due to the excessive inflammatory reaction, even with neuraminidase inhibitor use. The anti-inflammatory effect of anti-high-mobility group box-1 (HMGB1) monoclonal antibody (mAb) against influenza pneumonia has been reported. In this study, we evaluated the combined effect of anti-HMGB1 mAb and peramivir against pneumonia induced by influenza A (H1N1) virus in mice. Nine-week-old male C57BL/6 mice were inoculated with H1N1 and treated with intramuscularly administered peramivir at 2 and 3 days post-infection (dpi). The anti-HMGB1 mAb or a control mAb was administered at 2, 3, and 4 dpi. Survival rates were assessed, and lung lavage and pathological analyses were conducted at 5 and 7 dpi. The combination of peramivir with the anti-HMGB1 mAb significantly improved survival rate whereas the anti-HMGB1 mAb alone did not affect virus proliferation in the lungs. This combination therapy also significantly ameliorated histopathological changes, neutrophil infiltration, and macrophage aggregation by inhibiting HMGB1, inflammatory cytokines, and oxidative stress. Fluorescence immunostaining showed that the anti-HMGB1 mAb inhibited HMGB1 translocation from type I alveolar epithelial cells. In summary, combining anti-HMGB1 with conventional anti-influenza therapy might be useful against severe influenza virus infection.

Epidemiology of Pediatric Acute Encephalitis/Encephalopathy in Japan.

We studied the etiology of pediatric acute encephalitis/encephalopathy (pAEE) using epidemiological data obtained from a nationwide survey in Japan. Two-step questionnaires were sent to the pediatric departments of hospitals throughout the country in 2007, querying the number of the cases during 2005-2006 as the first step, and asking for the details of clinical information as the second step. In all, 636 children with pAEE (age ≤ 15 years) were enrolled. For the known etiology of pAEE (63.5% of the total cases), 26 microbes and 2 clinical entities were listed, but the etiology of 36.5% remained unknown. Influenza virus (26.7%), exanthem subitum (12.3%), and rotavirus (4.1%) were the most common, and the incidence of pAEE peaked at the age of 1 year. This trend was common among all etiologies. Among the neurological symptoms observed at the onset of pAEE, seizures were observed more often in patients aged ≤ 3 years, although abnormal speech and behavior were also common in older children. Undesirable outcomes (death and neurological sequelae) occurred at high rates in patients with any known etiology other than mycoplasma. In conclusion, these findings provide comprehensive insight into pAEE in Japan.

Serum Procalcitonin Levels in Acute Encephalopathy with Biphasic Seizures and Late Reduced Diffusion.

Procalcitonin (PCT) is used as a biomarker in severe infections. Here, we retrospectively investigated levels of serum PCT, C-reactive protein (CRP), and inflammatory cytokines (IL-6, TNF-α, and IFN-γ) in the second phase of patients with acute encephalopathy with biphasic seizures and late reduced diffusion (AESD). Nine AESD pediatric patients (4 men, 5 women; AESD group) admitted to Okayama University Hospital from 2010 to 2016 were compared with 10 control patients with febrile seizures (FS) (3 men, 7 women; FS group). Mean PCT concentrations (ng/mL) in the AESD and FS groups were significantly different, at 9.8 ± 6.7 and 0.8 ± 0.9, respectively (p = 0.0011). CRP (mg/dL) were 0.79 ± 0.89 and 1.4 ± 1.0 (p = 0.21), respectively; IL-6 (pg/mL) were 449.7 ± 705.0 and 118.3 ± 145.4 (p = 0.20), respectively; TNF-α (pg/mL) were 18.6 ± 12.5 and 16.6 ± 6.0 (p = 0.67), respectively; and IFN-γ (pg/mL) were 79.6 ± 158.5 and 41.9 ± 63.7 (p = 0.56), respectively. Ratios of PCT to CRP were 27.5 ± 34.2 and 3.2 ± 6.8 (p < 0.0001), respectively. The sensitivity and specificity in the diagnosis of AESD using a cutoff of PCT/CRP ratio of 1.0 were 100% and 80%, respectively. These results suggest that PCT and the PCT/CRP ratio are useful in auxiliary diagnosis of the second stage of AESD, and in AESD, PCT is likely to increase through a different mechanism.

Anti-high mobility group box-1 monoclonal antibody treatment of brain edema induced by influenza infection and lipopolysaccharide.

Encephalopathy is a major cause of influenza-associated child death and severe neurological sequelae in Japan, highlighting the urgent need for new therapeutic strategies. In this study, we evaluated the effects of anti-high mobility group box-1 monoclonal antibody (α-HMGB1) treatment on brain edema induced by influenza A virus (IAV) and lipopolysaccharide in 4-week-old BALB/c female mice. The results showed that administration of 7.5 mg/kg α-HMGB1 1 h after IAV (A/Puerto Rico/8/34) inoculation significantly alleviated brain edema at 48 h after IAV inoculation, as confirmed by the suppression of Evans Blue dye leakage and matrix metallopeptidase-9 mRNA expression in the brain. Moreover, we also observed suppression of oxidative stress and different cytokines in IAV-inoculated mice. The expression of plasminogen activator inhibitor-1 was also attenuated following treatment with α-HMGB1. Notably, α-HMGB1 treatment had no effect on virus propagation in the lung. In summary, anti-HMGB1 treatment may improve the prognosis in cases with influenza-associated encephalopathy by attenuating brain edema and reducing the inflammatory responses induced by HMGB1.

Local and Systemic Immune Responses to Influenza A Virus Infection in Pneumonia and Encephalitis Mouse Models.

OBJECTIVE: To compare local and systemic profiles between different disease pathologies (pneumonia and encephalitis) induced by influenza A virus (IAV). METHODS: An IAV pneumonia model was created by intranasal inoculation of C57BL/6 mice with influenza A/WSN/33 (H1N1) virus. Lung lavage and blood collection were performed on day 3 after IAV inoculation. Similarly, an IAV encephalitis mouse model was created by direct intracranial IAV inoculation. Cerebrospinal fluid (CSF) and blood collection were conducted according to the same schedule. Cytokine/chemokine profiles were produced for each collected sample. Then the data were compared visually using radar charts. RESULTS: Serum cytokine profiles were similar in pneumonia and encephalitis models, but local responses between the bronchoalveolar lavage fluid (BALF) in the pneumonia model and CSF in the encephalitis model differed. Moreover, to varying degrees, the profiles of local cytokines/chemokines differed from those of serum in both the pneumonia and encephalitis models. CONCLUSION: Investigating local samples such as BALF and CSF is important for evaluating local immune responses, providing insight into pathology at the primary loci of infection. Serum data alone might be insufficient to elucidate local immune responses and might not enable clinicians to devise the most appropriate treatment strategies.

Pulmonary inflammation and cytokine dynamics of bronchoalveolar lavage fluid from a mouse model of bronchial asthma during A(H1N1)pdm09 influenza infection.

Asthmatic patients present more rapid progression of respiratory distress after A(H1N1)pdm09 influenza infection than after seasonal infection. Here, we sought to clarify the pathophysiology of early deterioration in asthmatic patients after A(H1N1)pdm09 infection. Cytokine levels and virus titres in bronchoalveolar lavage fluid from mice with and without asthma after A(H1N1)pdm09 or seasonal H1N1 infection were examined. In asthma/A(H1N1)pdm09 mice, IL-6 and TNF-α levels peaked at 3 days post-infection and were higher than those in all other groups. IFN-γ levels in asthma/A(H1N1)pdm09 mice at 3 days post-infection were higher than in all other mice at any time point, whereas at 7 days post-infection, the levels were lowest in asthma/A(H1N1)pdm09 mice. Virus titres in asthma/A(H1N1)pdm09 mice were highest at 3 days post-infection, and decreased by 7 days post-infection, although the levels at this time point were still higher than that in any other group. Histopathological examination showed more inflammatory cell infiltration and lung tissue destruction in the asthma/A(H1N1)pdm09 group than in any other group. The distinct cytokine profiles in A(H1N1)pdm09-infected asthmatic mice indicated excessive inflammation and virus replication within a few days after infection. Thus, bronchial asthma could be a more exacerbating factor for pandemic influenza infection than for seasonal influenza infection.

Metabolic pathway catalyzed by Vanin-1 pantetheinase plays a suppressive role in influenza virus replication in human alveolar epithelial A549 cells.

Our previous analysis of gene expression profiles in the peripheral blood from patients with influenza A (H1N1) pdm09 pneumonia revealed elevated transcription levels of the vanin-1 (vascular non-inflammatory molecule 1, VNN1) gene, which encodes an epithelial ectoenzyme with pantetheinase activity involved in recycling coenzyme A. Here, to elucidate the role of VNN1 in influenza A virus (IAV) H1N1 infection, we investigated the change of VNN1 expression in the context of IAV infection and the effects of its related substances, i.e., its direct substrate pantetheine and its two metabolites pantothenic acid and cysteamine on the replication of IAV in the human alveolar epithelial carcinoma cell line A549. The messenger RNA expression of VNN1 in A549 cells was significantly increased (by 4.9-fold) after IAV infection under an elevated concentration of pantetheine. Moreover, VNN1 mRNA levels were elevated by > 100-fold in response to pro-inflammatory cytokines, especially TNF-α and IL-1ß. Pantetheine significantly reduced the IAV replication and IAV Matrix 1 (M1) mRNA levels when it was administered prior to and during infection. In addition, cysteamine treatment during IAV infection significantly reduced the viral replication and IAV M1 mRNA levels, whereas pantothenic acid did not. These findings suggest that the metabolic pathway catalyzed by VNN1 pantetheinase plays a suppressive role in IAV infection in the respiratory tract, especially in severe conditions under hypercytokinemia.

Monitoring of human herpesviruses-6 and -7 DNA in saliva samples during the acute and convalescent phases of exanthem subitum.

The amounts of the DNAs of human herpesviruses-6 (HHV-6) and -7 (HHV-7) in saliva samples were monitored during the acute and convalescent phases of exanthem subitum (ES) to elucidate the kinetics of virus shedding after ES. A total of 247 saliva samples were collected from 17 children (5 males and 12 females: 8-31 months old at onset). The monitoring period ranged from 152 to 721 days after onset, and in 15 children it was longer than 1 year. Among the 17 cases, 16 were attributed to HHV-6B, while a single case was attributed to HHV-7. Detection rates and average amounts of HHV-6 DNA in saliva samples after ES attributed to HHV-6B were low in the acute phase, increased to the maximum in the convalescent phase at 3-7 months, and then decreased. In addition, to investigate the source of infection, saliva samples from the older siblings (age 3-9 years) and parents of ES patients and children with a history of ES were also examined. The detection rate of HHV-6 DNA in saliva samples from 3- to 9-year-old children was significantly higher than the rate in adult saliva samples. Taken together, these findings suggest that the saliva of children in the convalescent phase of ES might be a more likely source of HHV-6 infection than that of adults. J. Med. Virol. 89:696-702, 2017. © 2016 Wiley Periodicals, Inc.

Analysis of the synthetic house-tree-person drawing test for developmental disorder.

BACKGROUND: Some patients cannot draw three subjects on the same page during the synthetic house-tree-person drawing test (S-HTP). We call this phenomenon "no synthetic sign". The aim of this study was to clarify the pathological meaning of no synthetic sign and investigate its use for the early detection of developmental disorders at a pediatric primary care center. METHODS: We administered the S-HTP to 283 people who consulted the child psychosomatic medical clinic of Okayama University Hospital in 2007-2012. We diagnosed developmental disability based on DSM-IV-TR criteria and compared findings between the different diagnostic groups. RESULTS: A total of 241 patients completed the S-HTP (S-HTP group) and 22 patients were not able to complete the S-HTP, but did complete the HTP (an original version of the S-HTP) or tree test (HTP group). Significantly more people in the HTP group had autism spectrum disorder (ASD) compared with the S-HTP group. Full-scale intelligence quotient was significantly lower in the HTP group compared with the S-HTP group. CONCLUSIONS: There were two types of patients with no synthetic sign. The first involved patients with a suspected mental age younger than 5 years 11 months. The second type consisted of patients with ASD. Although drawing ability reflects multiple domains, it may help in early identification of children with developmental problems and facilitate earlier initiation of interventions.

Inhibitory Effects of Edaravone, a Free Radical Scavenger, on Cytokine-induced Hyperpermeability of Human Pulmonary Microvascular Endothelial Cells:A Comparison with Dexamethasone and Nitric Oxide Synthase Inhibitor.

Lung hyperpermeability affects the development of acute respiratory distress syndrome (ARDS), but therapeutic strategies for the control of microvascular permeability have not been established. We examined the effects of edaravone, dexamethasone, and N-monomethyl-L-arginine (L-NMMA) on permeability changes in human pulmonary microvascular endothelial cells (PMVEC) under a hypercytokinemic state. Human PMVEC were seeded in a Boyden chamber. After monolayer confluence was achieved, the culture media were replaced respectively by culture media containing edaravone, dexamethasone, and L-NMMA. After 24-h incubation, the monolayer was stimulated with tumor necrosis factor-α (TNF-α) and interleukin-1ß (IL-1ß). Fluorescein-labeled dextran was added. Then the trans-human PMVEC leak was measured. Expressions of vascular endothelial-cadherin (VE-cadherin) and zonula occludens-1 protein (ZO-1) were evaluated using real-time quantitative polymerase chain reaction and immunofluorescence microscopy. The results showed that TNF-α＋IL-1ß markedly increased pulmonary microvascular permeability. Pretreatment with edaravone, dexamethasone, or L-NMMA attenuated the hyperpermeability and inhibited the cytokine-induced reduction of VE-cadherin expression on immunofluorescence staining. Edaravone and dexamethasone increased the expression of ZO-1 at both the mRNA and protein levels. Edaravone and dexamethasone inhibited the permeability changes of human PMVEC, at least partly through an enhancement of VE-cadherin. Collectively, these results suggest a potential therapeutic approach for intervention in patients with ARDS.

Anti-high mobility group box-1 monoclonal antibody treatment provides protection against influenza A virus (H1N1)-induced pneumonia in mice.

INTRODUCTION: Provision for the emergence of an influenza pandemic is an urgent issue. The discovery of a novel anti-influenza therapeutic approach would increase the effectiveness of traditional virus-based strategies. This study was undertaken to evaluate the therapeutic effects of anti-high mobility group box-1 (HMGB1) monoclonal antibody (mAb) treatment on influenza A virus (H1N1)-induced pneumonia in mice. METHODS: Nine-week-old male C57BL/6 mice were inoculated with H1N1, then anti-HMGB1 mAb or control mAb were administered intravenously at 1, 24 and 48 hours after H1N1 inoculation and the survival rate was analyzed. Lung lavage and histopathological analysis were performed on days 3, 5, 7 and 10 after inoculation. RESULTS: Anti-HMGB1 mAb significantly improved the survival rate of H1N1-inoculated mice (1 out of 15 versus 8 out of 15 deaths in the anti-HMGB1 mAb-treated group versus the control mAb-treated group, p < 0.01), although the treatment did not affect virus propagation in the lungs. The treatment also significantly attenuated histological changes and neutrophil infiltration in the lungs of H1N1-inoculated mice. This was associated with inhibition of HMGB1 and suppression of inflammatory cytokine/chemokine expression and oxidative stress enhancement, which were observed in H1N1-inoculated mice. The expression of receptor for advanced glycation end products and nuclear factor κB was attenuated by the treatment. CONCLUSIONS: Anti-HMGB1 mAb may provide a novel and effective pharmacological strategy for severe influenza virus infection in humans by reducing the inflammatory responses induced by HMGB1.

Effects of the elective introduction of extracorporeal membrane oxygenation on outcomes in pediatric myocarditis cases.

Aim: To investigate the necessary indicators to diagnose pediatric myocarditis and choose appropriate candidates for extracorporeal membrane oxygenation therapy. Methods: We retrospectively reviewed the medical records of children aged <16 years of age who were diagnosed with myocarditis and admitted to the pediatric intensive care unit in a Japanese children's hospital from 2002 to 2013. We collected demographic data and symptoms and signs during the entire clinical course, investigated the survival and neurological outcomes, and identified the predictors of death. Results: Twenty-nine patients (median age, 5 years) met the inclusion criteria. Fever and gastrointestinal symptoms occurred in approximately 80% of the patients as initial symptoms and central nervous system symptoms were the most frequent symptom on emergency presentation (41%). Extracorporeal membrane oxygenation was administered to 16 patients; of these, five died. Of the 24 surviving patients, 23 achieved favorable neurological outcomes. Four of eight patients died following cardiopulmonary resuscitation-triggered extracorporeal membrane oxygenation, and one of eight died following elective extracorporeal membrane oxygenation. Multivariate analysis using stepwise logistic regression analysis revealed creatinine level as an independent predictor of death. Conclusion: It is important to consider myocarditis when evaluating children with gastrointestinal or central nervous system symptoms. The elective introduction of extracorporeal membrane oxygenation before the completion of end-organ dysfunction has a positive effect on outcomes in pediatric myocarditis cases. Transfer to an institution that can initiate extracorporeal membrane oxygenation support should be promptly considered when managing pediatric myocarditis.

Brain magnetic resonance imaging in acute phase of pandemic influenza A (H1N1) 2009--associated encephalopathy in children.

Pandemic influenza A (H1N1) 2009 has been shown to be associated more with neurological complications than the seasonal influenza virus. In this study, we focused on the clinical usefulness of magnetic resonance imaging (MRI) in the acute phase of influenza A (H1N1) 2009-associated encephalopathy. A questionnaire was distributed to pediatric and general hospitals in Japan that treat children with encephalopathy. We conducted a questionnaire-based study involving the collection of information regarding 207 patients with encephalopathy. Brain MRI was performed in 97 of these 207 patients in the age group of 9 months to 15 years (mean, 7.5 years) within 48 hours after the development of encephalopathy symptoms. Sixty-six patients (68%) showed normal imaging. Diffuse brain edema was visible in five patients and an abnormal signal in the deep gray matter in two patients which is consistent with acute necrotizing encephalopathy. Abnormal signals of the splenial lesion, subcortical white matter (bright tree appearance), and cortical area were observed in 15, 1, and 8 patients, respectively. From our findings based on the questionnaire results, we suggest that MRI is useful for determining fatal cases of pandemic influenza A (H1N1) 2009 infection when performed in the acute phase. However, MRI is not useful in predicting the development of sequelae.