The coronavirus disease 2019 (COVID-19) pandemic has affected hundreds of thousands of people. The authors performed a comprehensive literature review to identify the underlying mechanisms and risk factors for severe COVID-19 in children. Children have accounted for 1.7% to 2% of the diagnosed cases of COVID-19. They often have milder disease than adults, and child deaths have been rare. The documented risk factors for severe disease in children are young age and underlying comorbidities. It is unclear whether male gender and certain laboratory and imaging findings are also risk factors. Reports on other potential factors have not been published.

Infection from severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), though mainly a respiratory disease, can impair many systems, including causing hematological complications. Lymphopenia and hypercoagulability have been reported in adults with coronavirus disease 2019 (COVID-19) and are considered markers of poor prognosis. This review summarizes the hematological findings in children with SARS-CoV-2 infection. The majority of infected children had a normal leukocyte count, while the most common white blood cell abnormality was leukopenia. Lymphopenia, which may be a marker of severe disease, was rarer in children than in adults, possibly due to their immature immune system or due to the less severe manifestation of COVID-19 in this age group. Age may have an impact, and in neonates and infants the most common abnormality was lymphocytosis. Abnormalities of red blood cells and platelets were uncommon. Anemia and hypercoagulability were reported mainly in children presenting the novel multisystem inflammatory syndrome (MIS) associated with SARS-CoV-2.

Background: A term neonate presented with persistent severe thrombocytopenia, elevated liver enzymes, conjugated hyperbilirubinemia, hepatosplenomegaly, and mild hypotonia.Observations: A thorough workup for infections, congenital thrombocytopenias, and neonatal malignancies was negative. Because of increased anti-SARS-CoV-2 IgG antibodies after maternal COVID-19, multisystem inflammatory syndrome of neonates was considered and intravenous immunoglobulin was administered. The clinical condition of the neonate deteriorated and due to laboratory evidence of hyperinflammation, hemophagocytic lymphohistiocytosis was suspected, and treatment with etoposide and dexamethasone was initiated with temporary stabilization. Gaucher disease type 2 was eventually diagnosed. Conclusion:Gaucher disease can rarely present in neonates as hemophagocytic lymphohistiocytosis.

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Clinicians should be aware of the possibility, although rare, of AHT developing during triptorelin administration in childhood, specifically in patients at increased risk of AHT, such as those with WBS.