COVID-19 compared with flu

Researchers in Weill Cornell Medicine in New York compared the rates of stroke in COVID-19 and influenza patients.

COVID-19, caused by the SARS-CoV-2 virus, mainly affects the respiratory system causing fever, cough, shortness of breath, and in some cases severe respiratory distress. However, as medical experts learn more about the illness, they have discovered how COVID-19 can affect other body systems. In particular, SARS-CoV-2 infection can lead to a “hypercoagulable” state, meaning that blood clots may form in the circulatory system. This could increase the risk of stroke (blood clots in the brain), or other clotting complications.

COVID-19 causes a “hypercoagulable” state that may increase stroke risk

Early reports from China, France and the United States suggested that COVID-19 increases the risk of stroke. However, these studies did not compare the risk with that of other viral respiratory infections such as influenza, which is also a known risk factor for stroke. Researchers at Weill Cornell Medicine, New York, compared the rates of stroke in COVID-19 and influenza patients. They recently reported their findings in JAMA Neurology.

In two New York City hospitals, the researchers collected data from adult patients attending between March 2 and May 2, 2020, with confirmed COVID-19 and adult patients attending between January 1, 2016, and May 31, 2018, with influenza. The rates of stroke between the two patient groups were calculated and compared by a panel of neurologists.

A total of 31 of 1916 patients (1.6%) with COVID-19 had acute stroke, compared with 3 of 1486 (0.2%) of influenza patients. The risk of stroke in COVID-19 patients was almost eight times higher than for influenza patients (odds ratio, 7.6), even after adjusting for factors that could have affected the outcome such as age, sex, race, vascular risk factors, viral symptoms, and intensive care unit admission.

Stroke risk higher in COVID-19 compared with flu

The researchers concluded that COVID-19 patients appear to be at a higher risk of stroke than influenza patients. These initial findings need to be confirmed with further studies, but the researchers recommend that doctors treating COVID-19 patients are vigilant for stroke symptoms so that they can take preventative measures or early actions such as using anti-clotting treatments.

Written by Julie McShane, MA MB BS


Merkler AE, Parikh NS, Mir S, et al. Risk of ischaemic stroke in patients with coronavirus disease 2019 (COVID-19) vs patients with influenza. JAMA Neurol. Published online July 2, 2020. Doi:10.1001/jamaneurol.2020.2730

Image by PIRO4D from Pixabay 

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