Study Offers New Evidence of Neuro-Axonal Damage in Mild-to-Moderate Cases of SARS-CoV-2

Findings from a new study have offered first-time evidence of neuro-axonal damage in mild-to-moderate cases of SARS-CoV-2 and validated serum neurofilament light chain (sNfL) as a highly specific biomarker to measure and monitor damage during and post infection.

Quanterix Corporation (Billerica, MA, USA) performed quantitative testing using its sNfL Assay and Simoa technology to show that COVID-19 can affect the neurological integrity of adult patients who experience a mild-to-moderate form of the virus. The study offers new evidence of SARS-CoV-2’s neuro-destructive capabilities as it relates to less severe cases. The results also support the utility of sNfL as a screening and monitoring tool for measuring neuronal injury throughout COVID-19 disease progression and recovery, as well as lay the foundation for the evaluation of potential long-term neurological impact following COVID-19 recovery.


While COVID-19 manifests predominantly as a respiratory illness, numerous accounts and preliminary research studies connect the virus to multiple neurological conditions, including headache, stroke, cognitive loss, anosmia (loss of smell) and ageusia (loss of taste). This body of evidence demonstrating the virus’s impact on the nervous system continues to grow, with recent research linking COVID-19 to delirium, brain inflammation, stroke and nerve damage. However, experts have cautioned that it could require years of study to fully understand the long-term effects of these symptoms.

In the new study, the researchers analyzed a cohort of 100 healthcare workers without known co-morbidities, composed of 84 females and 16 males. The subjects were stratified by infection status and age, and their sNfL concentrations were measured approximately 23 days after disease onset and again approximately 35 days later using the Simoa NF-light kit on the Simoa HD-X Analyzer. Notably, all positive patients reported mild-to-moderate symptoms with recovery within one-to-three weeks and showed no or only minor neurological symptoms. The results revealed that COVID-19 status was significantly associated with sNfL when controlling for age and gender. In patients with two sNfL measurements, sNfL levels were highly correlated. As NfL is a well-established marker for neuronal damage, elevated levels in serum suggest acute or chronic neuro-axonal damage as a result of COVID-19, even in mild or moderate forms.

“It’s becoming alarmingly clear just how much we still do not understand about COVID-19 and how our testing regimen needs to improve in accuracy and precision,” said Kevin Hrusovsky, Chairman, Chief Executive Officer and President, Quanterix and Founder, Powering Precision Health (PPH). “Harnessing the power of biomarkers to shed light on these scientific mysteries and improve testing precision is the collective missions at Quanterix and PPH. We’re compelled to work closely with researchers across our global syndicate to apply our breadth of expertise and technologies – as generated by hundreds of studies across Alzheimer’s disease, Parkinson’s disease, Multiple Sclerosis (MS) and other neurological conditions – to understanding the short and long-term neurological impacts of COVID-19. This study represents a significant step toward this goal because it provides novel data on the virus’s neuro-axonal impact and validates a key means of studying it through sNfL, which will be critical to public health in the years ahead.”

“We’re proud to share this paper with the scientific community at-large, as we believe it offers important insight into neurological ramifications among a cohort that represents the vast majority of COVID-19 cases,” said Jens Kuhle, MD, professor at University of Basel and a lead researcher on the study. “Preliminary research conducted early on in the pandemic mainly assessed hospitalized, and therefore, the most severe patients’ neurological response. In contrast, our study evaluated the virus’s neuron-destructive capabilities in instances where patients experienced mild to no symptoms and had no known co-morbidities that could exacerbate neurological declines. The ability to not only see but also accurately quantify NfL through an easily administered blood test using the ultra-sensitive Simoa platform was instrumental to the success of this project, and we believe it will also be important to the feasibility of long-term studies.”

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