Scientists believe they may have discovered a blood test that could predict which patients are most likely to be COVID-19 long-haulers – or those that retain some health issues long after testing negative for the disease.
A study just published in the journal Nature Communications found that people who go on to develop long COVID have lower levels of certain antibodies in their blood soon after they are infected with the coronavirus. Which means a blood test for those antibodies could serve as a predictor of who may become a COVID long-hauler.
If the work of these researchers could be verified and consistently duplicated through larger studies, the findings could help scientists develop a test to predict who may continue to suffer from symptoms weeks, months, and even years following infection.
“We want to be able to recognize and identify, as early as possible, who is at risk of developing long COVID,” said Dr. Onur Boyman, an author of the new study and a researcher in the department of immunology at University Hospital Zurich.
Long Covid, a poorly understood condition for which there is no standard definition, diagnosis, or treatment, has vexed doctors and researchers worldwide since the pandemic began.
The precise number of long Covid patients, often also referred to as “long haulers,” is unclear, though it’s been estimated that one-third of Covid patients overall may experience symptoms for at least a month.
Any early insights into which patients may end up becoming long-haulers are welcome, outside experts said.
Charles Downs, a researcher into long Covid and an associate professor in the School of Nursing and Health Studies at the University of Miami, called the research “very promising.”
“There is no single test, no imaging study, that can be used to give a diagnosis” of long Covid, he said. “This helps move us in that direction.
While promising, several caveats apply to the new research. Patients in the study were infected between April 2020 and August 2021, before the omicron variant took hold.
It is uncertain, therefore, whether the findings would apply to those who may develop long Covid following an omicron infection.
What’s more, the study did not take into account the vaccination status of participants. Many of the long Covid patients became ill early in 2020 before vaccines were available.
“It would be important to look to see whether these markers are still predictive in vaccinated people as more of the world is vaccinated or has prior infection,” Claire Steves, a senior clinical lecturer at Kings College London, said in a statement.
Still, if confirmed in larger studies, and taking those considerations into account, the research could be “an important step forward towards directing resources in post-Covid-19 clinics to those who need them the most,” Dr. Kartik Sehgal, a long Covid researcher and medical oncologist at the Dana-Farber Cancer Institute in Boston, wrote in an email.