Study finds no reliable biomarkers for long COVID

The COVID-19 pandemic has had a significant impact on millions worldwide and put a lot of pressure on healthcare systems.

While most people recover from the initial infection, many others keep experiencing symptoms for weeks and months after. This is known as long COVID and can provide a significant health challenge.

More than 200 symptoms have been associated with long COVID, with some of the most common symptoms being extreme fatigue and memory issues, sometimes referred to as brain fog.

Past studies have shown several risk factors for developing long COVID, including pre-existing chronic conditions and severe acute illness. But they’ve also struggled to identify reliable biomarkers for diagnosing long COVID.

Researchers working to identify reliable biomarkers

A study looked at residents of the Faroe Islands who got COVID-19 during the early part of the pandemic.

A total of 324 people infected were eligible to participate in the study.

People who participated in the study were asked to complete a baseline and symptom questionnaire conducted over the phone six times in eight months.

The questionnaire consisted of 21 items and allowed participants to rate symptoms on a 0-to-3 scale.

Study follow-up

From September 2020 to March 2021, a follow-up study was conducted. Of the 324 original participants, 273 were in the clinical follow-up and 218 were in the final analysis.

After an average follow-up period of 192 days, 41% reported they had moderate or severe symptoms and were classified as having long COVID for the study’s statistical analyses.
The researchers also noted that the 41% in this study shouldn’t be considered as the amount of long COVID in the general population.

In a blood biomarker analysis, higher counts of neutrophils, which are the most common type of white blood cell that helps the immune system fight infections, were associated with long COVID but this was not confirmed in all the models.

In addition, the study found that the international normalized ratio (INR), which is a standardized measure of how quickly blood clots, was lower in participants who had long COVID than those who did not.

Even though lower INR is associated with long COVID, all the INR values in this study were within the normal range and the finding had no clinical significance.