**Abstract**

Pediatric cancer patients are immunocompromised, and the risks are higher in this population. Confirmed cases are defined as PCR (polymerase chain reaction) positive patients. The severity of infection is divided into four groups: asymptomatic/mild, moderate, severe, and critical, based on the clinical, laboratory, and radiological features. In the pediatric population, the COVID-19 disease has a mild course. Chemotherapy courses can be interrupted according to the symptoms and severity of the disease. Azithromycin, antivirals are used as a single agent or in combination. In critical patients, convalescent plasma, mesenchymal stem cells, tocilizumab, and granulocyte transfusions are administered. In recent studies, having hematological malignancy, stem cell transplantation, a mixed infection, and abnormal computerized tomography findings increase the severity of the disease and the need for an intensive care unit. Therefore, the patients and their families should be aware of a higher risk of severe forms than immunocompetent children.

**Keywords:** chemotherapy, COVID-19, immunocompromised, immunotherapy, pediatric oncology

## **1. Introduction**

Coronaviruses are zoonotic RNA viruses. SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the novel coronavirus, belongs to the Betacoranovirus subgroup [1]. SARS-CoV-2's incidence in children varies (China: 2-12.3%, Italy: 1.2%, USA: 5%). The infection in pediatric cases is asymptomatic or mild. The median incubation period is 5-7 days. The primary source of transmission is respiratory droplets and direct contact. The primary tool for diagnosis is a real-time polymerase chain reaction test (RT-PCR) on samples. Eighty percent of children had household contact; ten percent were asymptomatic, fifty percent had a fever. Other symptoms are cough, respiratory distress, fatigue, myalgias, vomiting, diarrhea, anosmia, ageusia, sore throat. Children generally recover in 1-2 weeks. The case fatality rate in children is zero percent [2]. This benign course of the disease is related to the immune preparedness of children to a new pathogen. Immunologic mechanisms are also different in children compared with adults [3, 4]. Multisystem Inflammatory Syndrome in Children (MIS-C) is a rare postinfectious complication of SARS-CoV-2 infections; it is RT-PCR negative for SARS-CoV-2 virus but antibody positive [5].

Cancer treatment includes various immunosuppressive drugs [6]. It is well known that immunocompromised children have higher mortality and morbidity rates than the healthy population due to viral respiratory infections [7]. In the

pediatric oncology setting, the mortality rate in COVID-19 is reported up to 4% [8]. In COVID-19 relevant areas, the virus transmission rate is low in children with cancer. Cancer diagnosis, treatment, palliative care, hospital visits are interrupted because of the pandemic. Another concern is delayed cancer diagnosis, chemotherapy shortages, decreased availability of surgery, radiotherapy, supportive treatment, inadequate personal productive equipment, and drugs, especially in lowmiddle income countries [9, 10]. The most common cancer in the pediatric population is acute leukemia. In industrialized countries, the incidence of acute leukemia is a 40-60 age-standardized rate per million, one-third of all childhood cancers. Brain and spinal tumors are the second; lymphomas are the third most common tumors in industrialized countries [11]. Therefore, urgent treatment is critical and life-saving, especially in leukemia and lymphoma induction therapy [12]. Here we present an explanatory review of different approaches and experiences in this unique population.
