Tens of millions of people worldwide are believed to have long-term COVID-19, yet even four years after the pandemic was announced, there is still no reliable test for this mysterious illness, much less a treatment.
But it looks like early indicators of long-term Covid are finally being discovered, which is encouraging for potential future discoveries that could also shed light on other persistently enigmatic chronic syndromes.
A broad range of symptoms that people continue to experience weeks or months after first contracting the SARS-CoV-2 virus are referred to as "long covid."
The most typical ones include exhaustion, dyspnea, back pain, and fogginess in the brain.
A prominent study that was published last month revealed that the blood proteins of over 110 long-term Covid patients differed significantly from one another.
Senior author of the Science paper Onur Boyman, a Swiss researcher, told AFP that he thinks this is a "central puzzle piece" in explaining why Covid rages in some people's body for such a long time.
According to the researchers, in individuals with prolonged COVID, the complement system—a component of the immune system that typically eliminates pathogens by destroying contaminated cells—remains active, attacking healthy targets and causing tissue damage.
Boyman reported that there was a clear correlation between the improvement of complement system and recovery from long-term COVID-19 infection.
Boyman added that the researchers thinks this could lead to a future test. "It shows that long Covid is a disease and you can actually measure it," Boyman said.
Non-participating researchers issued a warning, pointing out that this "dysregulation" of the complement system could not account for all the various ways that Covid seemed to affect patients.
Nevertheless, according to Claire Steves, a professor of ageing and health at King's College London, it is "great to see papers coming out now showing signals which might start to explain long Covid".
"Every facet of my existence"
According to Lucia, a long-term Covid sufferer in the US who wished to remain anonymous to AFP, "studies like these bring us a lot closer to understanding" the illness.
She cited a another recent study in which it was discovered that long-term Covid patients' muscles had damage and fewer mitochondria, which may help explain why many of them get tired even after doing mild activity.
For Lucia, lengthy Covid turned stepping up the stairs to her flat into a daily challenge.
Lucia claimed she had no idea how Covid would "affect every aspect of my life -- including socially and financially" when she was initially diagnosed in March 2020.
A participant in the Patient-Led Research Collaborative, Lucia emphasized that individuals with extended COVID-19 experience more than just their numerous health problems.
They are often forced "to contend with disbelief or dismissal from the medical community or from within their social circles" , she added.
This week's BMJ study, which discovered that group rehab enhanced the quality of life for long-term Covid patients, brought attention to how important it is to support patients.
Why has it been so difficult?
Clinical epidemiologist Ziyad Al-Aly of Washington University in St. Louis stated that the reason Covid has been so difficult to treat for so long is that it is a "multi-system disease".
According to him, "our minds are trained to think about diseases based on organ systems," like lung or heart problems, AFP reported.
According to him, a more comprehensive explanation for "why and how acute infections cause chronic disease" may come from knowing the mechanisms underlying long-term COVID-19 infections.
This suggests that deciphering the enigma of extended Covid could strengthen efforts to combat other ailments including chronic fatigue syndrome or the so-called "long flu," which is the persistent symptoms following influenza.
Although the exact number of long-term Covid patients is difficult to ascertain, the World Health Organization estimates that it may account for 10–20% of all cases of the illness.
The US Centers for Disease Control and Prevention's research indicates that as new coronavirus variants have grown less severe, the proportion of persons who develop lengthy COVID has likely declined.
Researchers point out that vaccination against Covid has been demonstrated to dramatically lower the likelihood that individuals may contract long-term Covid, underscoring the need of booster injections.