An Epidemic of Parvovirus B19-Induced Aplastic Crises in Pediatric Patients with Hereditary Spherocytosis Following the COVID-19 Pandemic: A Single-Center Retrospective Study.

Background: Parvovirus B19 is the major cause of transient aplastic crisis in children with hereditary spherocytosis (HS) inhibiting erythropoiesis and leading to a severe drop in hemoglobin levels, requiring hospitalization and transfusional support. During the COVID-19 pandemic, the circulation of non-COVID respiratory viruses, such as parvovirus B19, initially declined but subsequently increased abruptly following the relaxation of containment strategies. Moreover, it remains unclear whether this has resulted in a rise in parvovirus B19-induced aplastic crises among individuals with HS. Methods: This retrospective, single-center study conducted at the Pediatric University Hospital of Bari (Italy) aims to describe the clinical characteristics and frequency of parvovirus B19-induced aplastic crises in pediatric patients with HS before and after the COVID-19 Public Health Emergency of International Concern (PHEIC, 30 January 2020-5 May 2023). The study was divided into four distinct periods: Period A: from 1 December 2018 to 31 December 2019, representing one year before the declaration of the PHEIC; Period B: from 1 June 2023 to 30 June 2024, representing one year after the cessation of the PHEIC; Period C: before 1 December 2018; Period D: from 1 January 2020 to 31 May 2023, which refers to the pandemic period. Results: A total of 30 patients (55% of the study population, n = 55) experienced a parvovirus B19-induced aplastic crisis. The frequency of these crises in Period B was significantly higher than in Period A (p < 0.0001). Conclusions: This study suggests a substantial increase in parvovirus B19-induced aplastic crises among children with HS following the COVID-19 outbreak indicating a potential impact of public health containment strategies on parvovirus B19 infection rates.