Background: A malfunction of the innate immune response in COVID-19 is associated with eosinopenia particularly in more severe cases. This study tested the hypothesis that this eosinopenia is COVID-19 specific and is associated with systemic activation of eosinophils.. Methods: Blood of 15 healthy controls and 75 adult patients with suspected COVID-19 at the ER were included before PCR testing and analyzed by point-of-care automated flow cytometry (CD10, CD11b, CD16 and CD62L) in the absence or presence of a formyl peptide (fNLF). 45 SARS-CoV-2 PCR positive patients were grouped based on disease severity. PCR negative patients with proven bacterial (n=20) or other viral (n=10) infections were used as disease controls. Eosinophils were identified with the use of the FlowSom algorithm. Results: Low blood eosinophil numbers (<100 cells/microL; p<0.005) were found both in patients with COVID-19 and with other infectious diseases albeit less pronounced. Two discrete eosinophil populations were identified in healthy controls both before and after activation with fNLF based on the expression of CD11b. Before activation, the CD11bbright population consisted of 5.4% (CI95% = 3.8, 13.4) of total eosinophils. After activation, this population of CD11bbright cells comprised nearly half the population (42.21%, CI95% = 35.9, 54.1). Eosinophils in COVID-19 had a similar percentage of CD11bbright cells before activation (7.6%, CI95% = 4.5, 13.6), but were clearly refractory to activation with fNLF as a much lower percentage of cells end up in the CD11bbright fraction after activation (23.7%, CI95% = 18.5, 27.6; p<0.001). Conclusion: Low eosinophil numbers in COVID-19 are associated with refractoriness in responsiveness to fNLF, which is likely caused by migration of fully functional cells to the tissue. Such homing might be beneficial as eosinophils have been implicated in viral killing.

ObjectiveThe quick Sequential Organ Failure Assessment (qSOFA) is developed as a tool to identify patients with infection with increased risk of dying from sepsis in non-intensive care unit settings, like the emergency department (ED). An abnormal score may trigger the initiation of appropriate therapy to reduce that risk. This study assesses the risk of a treatment paradox: the effect of a strong predictor for mortality will be reduced if that predictor also acts as a trigger for initiating treatment to prevent mortality.DesignRetrospective analysis on data from a large observational cohort.SettingED of a tertiary medical centre in the Netherlands.Participants3178 consecutive patients with suspected infection.Primary outcomeTo evaluate the existence of a treatment paradox by determining the influence of baseline qSOFA on treatment decisions within the first 24 hours after admission.Results226 (7.1%) had a qSOFA ≥2, of which 51 (22.6%) died within 30 days. Area under receiver operating characteristics of qSOFA for 30-day mortality was 0.68 (95% CI 0.61 to 0.75). Patients with a qSOFA ≥2 had higher odds of receiving any form of intensive therapy (OR 11.4 (95% CI 7.5 to 17.1)), such as aggressive fluid resuscitation (OR 8.8 95% CI 6.6 to 11.8), fast antibiotic administration (OR 8.5, 95% CI 5.7 to 12.3) or vasopressic therapy (OR 17.3, 95% CI 11.2 to 26.8), compared with patients with qSOFA <2.ConclusionIn ED patients with suspected infection, a qSOFA ≥2 was associated with more intensive treatment. This could lead to inadequate prediction of 30-day mortality due to the presence of a treatment paradox.Trial registration number6916.

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