Clinical deterioration during neutropenia recovery after G-CSF therapy in patient with COVID-19

Background: Granulocyte colony stimulating factors (G-CSFs) induce neutrophils proliferation and cytokines production. It has often been used to treat neutropenia without solid evidence of efficacy. It has been demonstrated that respiratory distress is associated with neutropenia recovery but not with G-CSFs. In general, G-CSFs are known to be safe and well tolerated in most clinical settings. However, the safety of G-CSFs in an overwhelming inflammatory disease like coronavirus disease 2019 (COVID-19) is largely unknown. Case summary: We report a case with COVID-19 and neutropenia who rapidly deteriorated after administration of G-CSF. Conclusion: We observed a faster neutropenia recovery than previously known after administration of G-CSF in our case and in three similar cases previously reported in literature. This rapid neutropenia recovery and the robust inflammatory response in COVID-19 raise concerns about G-CSF safety in patients with COVID-19.