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Editorials
throid short-term radioprotection requires a BMP4-dependent, self- renewing population of stress erythroid progenitors. J Clin Invest. 2010;120(12):4507-4519.
10. Xiang J, Wu DC, Chen Y, Paulson RF. In vitro culture of stress ery- throid progenitors identifies distinct progenitor populations and analogous human progenitors. Blood. 2015;125(11):1803-1812.
11. Flygare J, Rayon Estrada V, Shin C, Gupta S, Lodish HF. HIF1alpha synergizes with glucocorticoids to promote BFU-E progenitor self- renewal. Blood. 2011;117(12):3435-3444.
12. Hara H, Ogawa M. Erthropoietic precursors in mice with phenylhy-
COVID-19 and sickle cell disease
Laurel A. Menapace and Swee Lay Thein
drazine-induced anemia. Am J Hematol. 1976;1(4):453-458. 13.Chyla BJ, Moreno-Miralles I, Steapleton MA, et al. Deletion of Mtg16, a target of t(16;21), alters hematopoietic progenitor cell pro- liferation and lineage allocation. Mol Cell Biol. 2008;28(20):6234-
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14. Stadhouders R, Cico A, Stephen T, et al. Control of developmentally
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stress erythropoiesis. Exp Hematol. 2019;78:21-34 e23.
Sickle Cell Branch, National Heart Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA E-mail: SWEE LAY THEIN - sl.thein@nih.gov
doi:10.3324/haematol.2020.255398
The spread of the novel SARS-CoV-2 coronavirus (COVID-19) has resulted in widespread lockdowns
1,2 and an unprecedented number of deaths globally.
The pandemic has posed unique challenges to healthcare providers involved in the care of individuals with chronic conditions, balancing maintenance of necessary care with appropriate precautions to reduce their exposure to infec- tion. Patients with sickle cell disease (SCD) present multi- ple challenges due to the complexity of their condition, disease-related comorbidities, and need for frequent med- ical interventions. To date, there has been a paucity of published data on how COVID-19 may impact morbidity and mortality in SCD patients.
In this edition of Haematologica, Charkravorthy and col- leagues report associated outcomes in 10 UK patients infected with SARS-CoV-2.3 All patients had hemoglobin (Hb) SS disease with pre-existing co-morbidities, despite of this nine patients made a full recovery without receiv- ing COVID-19 directed therapies. Five patients were hos- pitalized and treated supportively; two patients who had a cough and hypoxia received early preventive simple transfusions; five patients were managed at home via close telephone contact. Of the 10 patients, seven were female (median age of 37 years); two received hydrox- yurea therapy and seven received regular blood transfu- sions (four exchange and three simple transfusions). Given that COVID-19 is an acute infectious pneumonia, most experts anticipated that SARS-CoV-2 infection would trig- ger acute chest syndrome (ACS) yet only one patient who died in this series had significant respiratory complica- tions. The patient who died was a 54-year-old female with severe asthma, alloimmunization, and a history of delayed hemolytic transfusion reactions which prevented routine transfusion. The patient had lymphopenia, throm- bocytopenia and elevated C-reactive protein (CRP), which have been identified as poor prognostic markers in COVID-19 patients.4 The authors acknowledge that the demographic and treatment characteristics of this cohort may have influenced the observed outcomes.
This edition also includes a report of 195 cases of sus- pected or confirmed SARS-CoV-2 infection as captured by 10 regional centers in a real time survey over a 4-week
period in the UK.5 Patients with SCD represented the majority of cases (n=166, 85.1%) with Hb SS disease as the most common genotype (Hb SS 64.1%; Hb SC 15.4%; other genotypes 5.6%) followed by thalassemia (n=26, 13.3%) and rare inherited anemias (n=3, 1.5%). While the incidence of ACS in the SCD cohort was not specified, red cell exchange was performed in 46 patients during the course of infection. A total of eight SCD patients required mechanical ventilatory support in the setting of respirato- ry failure; 11 of 13 deaths attributed to COVID-19 occurred in patients with SCD. A subset analysis of 76 hospitalized SCD patients with PCR confirmed SARS- CoV-2 showed that the patient age was significantly asso- ciated with mortality, with the most deaths occurring in those aged 50 and older (n=4). The authors noted that three patients aged 20-39 years in the subset succumbed to COVID-19 although details regarding the comorbid medical conditions were not provided. Unexpectedly, mortality was higher in females and was not associated with severity of disease but observed differences were insignificant. The cases reported to date represent 1.2% of the estimated 13,655 individuals with SCD per registry data in England. There was a low incidence of infection in children (n=20) and there were no pediatric deaths. Definitive conclusions regarding COVID-19 mortality rates in SCD cannot be drawn given inherent ascertain- ment bias and missing data in the survey.
The mild clinical course of COVID-19 in the King’s College Hospital SCD patients3 was similarly encountered in a case series of four patients from Chicago,6 all of whom presented with acute pain. Of the four patients, three received the usual supportive care but one patient, a 32-year-old male with Hb SS, developed ACS requiring intubation and exchange transfusion.
Two other centers reported COVID-19 pneumonia caus- ing ACS in SCD patients. A 21-year-old male with Hb S/β0 thalassemia on hydroxyurea therapy presented with acute chronic left hip pain and subsequently developed a cough with progressive hypoxia and evidence of new pulmonary infiltrates during his hospital course.7 SARS-CoV-2 PCR testing was positive during the second week of admission. In addition to antibiotic therapy, the patient was initiated
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