key: cord-0902098-n3jx2ry1 authors: Davido, Benjamin; Partouche, Bethsabee; Jaffal, Karim; de Truchis, Pierre; Herr, Marie; Pepin, Marion title: Eosinopenia in COVID-19: what we missed so far? date: 2021-02-18 journal: J Microbiol Immunol Infect DOI: 10.1016/j.jmii.2021.01.013 sha: f4b6fecb77e54a17b110ee0edf57104d7f9a3bdb doc_id: 902098 cord_uid: n3jx2ry1 nan We have read with great interest the article published by Outh et al. concerning the use of 2 peripheral eosinopenia to predict the medical causes of admission in a medicine ward during 3 the first wave of COVID-19 (n=121) 1 . 4 The title of the article can be misleading while it states that eosinophil count (EC) below 5 100/mm 3 is highly evocative of COVID-19, meanwhile conclusion supports that a threshold 6 below 10/mm 3 is more relevant. In the present study the control group is heterogeneous, with 7 patients suffering from respiratory tract infections with a negative SARS-CoV-2 PCR (n=14), 8 patients with other viruses or bacterial infections (n=20), and patients with other non-9 infectious diagnoses (n=30). Therefore, at baseline the CRP level already differs significantly 10 between the 2 groups (Table 2) , with a median CRP value of 69.8 mg/L in the COVID-19 11 group versus 14.7 mg/L in the non-COVID-group (p=0.001). In the same way, Li et al. 12 already described that eosinopenia (<20/mm 3 ) was associated with COVID-19 in China 2 , but 13 authors highlighted that EC had to be interpreted in the light of the CRP level, considering 14 their control group had a normal CRP value (<4 mg/L). 15 To better approach the use of eosinopenia, it must be reminded that there is no consensual 16 threshold and that normal value for EC is ranging from 1 to 3% of total leukocytes 3 . Eosinopenia <100/μL as a 41 marker of active COVID-19: An observational prospective study Eosinopenia is a reliable marker of sepsis on 56 admission to medical intensive care units Development and Validation of a Prediction 58 Model for Mortality and Adverse Outcomes Among Patients With Peripheral Eosinopenia on 59 Admission for Clostridium difficile Infection Echappement aux anti-infectieux et pharmaco épidémiologie, 78180 Montigny-le