In a new study, researchers found a rapid laboratory test, the eosinophil count, readily obtained from a routine complete blood cell count (CBC) can aid in the early recognition of COVID-19 in patients, as well as provide prognostic information.
The eosinophil is a specialized cell of the immune system.
The research was conducted by a team at Coney Island Hospital in Brooklyn.
Current testing, which relies on diagnosis of COVID-19 by nasopharyngeal swab PCR assay, remains unreliable due to variable turnaround time and a high false-negative rate.
In the study, the team found that the absence of eosinophils can help with early diagnosis, and in general, a persistent low cell count is linked to a poor prognosis for the patient.
They say the review of the eosinophil count can be a useful tool in deciding whether to promptly isolate someone and initiate specific therapies while waiting for confirmatory test results.
In the study, eosinopenia correlated with the diagnosis of COVID-19, and its persistence correlated with high disease severity and low rates of recovery.
Low eosinophil count, or eosinopenia, is defined as having < 100 cells/microliter. A healthy range is typically between 100-400 cells/microliter.
The trend of the eosinophil count has been known to correlate with viral infections, but researchers did not know the correlation was so strong in the case of COVID-19.
The researchers compared the eosinophil results of routine CBC from the first 50 admitted COVID-19-positive patients with the eosinophil results of 50 patients with confirmed influenza infection.
Of the patients with COVID-19, 60% had zero eosinophils at presentation, compared to 16% of influenza patients.
An additional 28% of COVID-19 patients had zero eosinophils within 48 hours of admission, thus a total of 88% had zero eosinophils during hospitalization.
The team says in COVID-19, a disease that has substantial symptom overlap with influenza, eosinopenia could help to distinguish which patients likely have COVID-19.
In addition, continued low counts of eosinophils trended with high mortality rates. Patients whose eosinophil count increased tended to have better disease outcomes.
One author of the study is Muhammad M. Zaman, MD, an infectious disease specialist.
The study is published in The Journal of the American Osteopathic Association.
Copyright © 2020 Knowridge Science Report. All rights reserved.
