The First Case of a Child Infected with SARS-CoV-2 Omicron Variant in Japan, December 2021.

We report the first pediatric patient infected with the Omicron variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Japan. The patient was a one-year-old boy who resided in Japan. He went abroad with his parents from November 12, 2021 to November 28, 2021 and had no known contact with coronavirus disease (COVID-19) patients there. Upon arrival at the Narita International Airport on November 28, 2021, his father tested positive for SARS-CoV-2 via a quantitative antigen test. Because the boy and his mother tested negative for SARS-CoV-2, they quarantined together at a hotel separately from his father. On December 4, 2021, the boy tested positive by reverse-transcription polymerase chain reaction (RT-PCR) for SARS-CoV-2, without symptoms, and was hospitalized with his mother; he and his father were both found to be infected with the SARS-CoV-2 Omicron variant. The boy was not vaccinated against COVID-19. RT-PCR results were negative starting on December 20, 2021. The incubation period and required period for negative conversion of SARS-CoV-2 RNA of the Omicron variant case were similar to those of the cases of conventional strains. We should carefully consider the potential of the SARS-CoV-2 Omicron variant to spread widely among unvaccinated children.

Adapting pediatric health care responses to the COVID-19 pandemic in Japan: A clinical perspective.

The COVID-19 pandemic required our pediatric health care staff to adjust to many irregularities and solve serious issues in our routine clinical practice. In outpatient clinics, many children exhibited common cold symptoms that mimic COVID-19, thus we initially screened patients via an interview form, then later via SARS-CoV-2 antigen test. Cluster infections were entirely avoided by following systematic, everyday precautions. Patientsquality of life has been difficult to maintain during the pandemic, due to social and staffing restrictions. Other unexpected repercussions - such as an unexpected lack of seasonal virus infections, then a respiratory syncytial (RS) virus outbreak - required agile management of hospital resources. While we must continue to adapt our treatment programs in response to the evolving COVID-19 crisis, it remains essential to support the well-being of children through regular health check-ups, mental health support, educational opportunities, proper socialization, and close communication with parents and families.

[Hematological neoplasia associated with primary mediastinal germ-cell tumor treated with hematopoietic stem cell transplantation].

The occurrence of a primary mediastinal germ cell tumor and hematological neoplasia provides a poor prognosis that is known to be fatal at a median of 6 months after onset. We report the case of a 15-year-old male who was treated with chemotherapy and hematopoietic cell transplantation based on a report of a surviving case. At diagnosis, the patient had an unresectable mediastinal tumor with elevated alpha-fetoprotein and human chorionic gonadotropin levels and acute megakaryoblastic leukemia. We prioritized treatment with chemotherapy for the tumor owing to the oncological emergency. We then performed leukemia induction therapy and achieved complete remission. Although we used CDDP in combination with intensive therapy, the mediastinal tumor grew too large for it to be safely resected. We transplanted bone marrow from the patient's human leukocyte antigen-haploidentical sibling upon conditioning with busulfan-melphalan. After 44 days, the leukemia recurred in the patient's central nervous system. This was followed by various post-transplant complications, and the patient died of organ failure that was associated with infectious diseases. At necropsy, a poorly engrafted bone marrow was observed. The mediastinal tumor was primarily necrotic, although some immature teratoma components were observed. No leukemic precursor cells were detected. Residual mediastinal tumors may be associated with the recurrence of leukemias. We seek a treatment strategy that enables early tumor resection and high-dose chemotherapy. Further case studies are warranted along with the development of effective treatment methods.