An international team of scientists has found distinct changes in the blood of people with long Covid, suggesting a potential strategy to diagnose and perhaps treat a mysterious condition that takes many forms.
Long Covid comprises the lingering and often debilitating symptoms experienced by some people after their initial bout of Covid-19.
The important study, published Jan 18 (2024) in the journal Science, adds to our understanding of this chronic condition by revealing shifts in proteins that the body produces in response to inflammation that may persist months after infection.
It also detected blood clots and tissue injury.
“We identified common patterns in long Covid patients not recovered at six months after acute infection”, compared to healthy patients, wrote the team, a collaboration of scientists from the United States, Switzerland, Sweden and the United Kingdom.
There is tremendous need to diagnose and find effective ways to treat long Covid, a constellation of symptoms that include exhaustion, migraines, brain fog and nausea.
Although its prevalence is difficult to estimate, surveys suggest that long Covid may afflict 5.3% to 7.5% of people infected by the SARS-CoV-2 virus.
The more vaccine doses you get, the less likely you are to get it.
One dose of vaccine reduces the risk by 21%, two doses by 59%, and three or more doses by 73%, according to a recent study.
In long Covid, the body’s immune response doesn’t stop fighting even though the initial infection has long passed.
Experts don’t know why, but research from the University of California, San Francisco, in the US has revealed tiny pieces of the SARS-CoV-2 virus, perhaps hidden in tissue, that persists long after infection.
There is mixed evidence for the effectiveness of the antiviral drug Paxlovid in preventing long Covid.
There is a desperate need for a diagnostic test and treatment for long Covid.
Currently doctors are treating the symptoms, rather than the underlying cause.
The new findings are important because “they demonstrates dysfunction, which is important to patients,” said advocacy group MEAction scientific and medical outreach director Jaime Seltzer.
The group advocates for patients with long Covid and myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS), which is caused by other viral infections.
“Secondly, they point the way to potential treatments, and even possibly mechanisms” of disease, she said.
This paper builds on our understanding of long Covid by connecting the changes that occur during an acute infection to longer-term abnormalities in markers of blood cell function, said Zuckerberg San Francisco General Hospital infectious disease physician Dr Michael Peluso.
He is studying the biological mechanisms that drive long Covid and the infection’s long-term impact on health.
“It suggests that there is a relationship between the virus, its immune effects and changes in certain blood coagulation pathways,” he said.
Although the study represents another step forward for understanding the science of long Covid, it will not immediately change the approach to diagnosing or treating the condition, he added.
“We need more investment in larger studies to build upon these findings, as well as clinical trials to test whether altering some of the abnormalities that have been found here could result in symptomatic benefit,” he said.
In the new study, scientists analysed changes in the blood of 113 patients who either fully recovered from Covid-19 or developed long Covid, as well as healthy people.
Specifically, they measured the levels of 6,596 different proteins in study participants over a year, then sampled the blood again six months and a year later.
Proteins act like keys that fit in multiple locks on the surface of cells.
Changes in proteins mean that cellular processes are altered.
The team found that patients with long Covid showed changes in the system of proteins that combats pathogens, like viruses. Dysregulation of these proteins could be contributing to the tiny “microclots” sometimes seen in long Covid patients.
This type of dysregulation has also been seen in people with other persistent infection-related illnesses, such as chronic fatigue syndrome, said Seltzer.
It’s the body’s way of adapting, she said.
There are caveats though with this study.
With only 113 patients, it was relatively small.
Many participants were so sick that they needed hospitalisation, which could have influenced results.
Finally, it only studied changes within a year of infection; three to five years later, they may be different markers in the blood, said Seltzer.
These features suggest potential interventions, wrote Wolfram Ruf of the Center for Thrombosis and Hemostasis in Germany, in a commentary that accompanied the report.
Perhaps anti-inflammatory drugs would help; anti-coagulants might reduce the risk of dangerous blood clots.
“Eventually, the hope is that some of these findings can translate into the clinic, but we are still a ways away from that,” said Dr Peluso.
“We need to keep up the momentum to get answers for the tens of millions of people with this disabling condition.”
-By Lisa M. Krieger/The Mercury News/Tribune News Service