Long COVID-19 is increasingly becoming a perplexing condition for medical experts, as people who have long recovered from their illness continue to exhibit symptoms, ranging from loss of taste or smell to brain fog to kidney disease.
Now, a team of Yale University researchers is working on understanding how exactly the COVID-19 virus affects human bodies long-term, with several hypotheses being tested.
What the Yale team and others are seeking to understand is what's the immediate consequence of the virus that puts people at risk, as well as how it can impact people long-term.
"Even people who are asymptomatic or only mildly affected by the virus can sometimes have, what appears to be largely consequential long-term health issues," said Dr. Harlan Krumholz, professor of cardiology with the Yale School of Medicine and the director of the Center for Outcomes Research and Evaluation.
Sometimes these issues are so severe that whole lives can be disrupted, "they can barely function," Krumholz told Holly Quan and Matt Bigler on KCBS Radio's "Ask an Expert" on Tuesday.
"What's scary about this, what’s concerning about this is that the range of symptoms is just so broad," he said. "Sorting through this, trying to figure out what’s the underlying mechanism, how is this connected to the virus," is what researchers are seeking to understand.
The theories being developed fall into two categories, one of which is that the virus never truly leaves the body and is still causing "mischief," said Krumholz, similar to other viruses, like herpes. For instance, if someone has had chickenpox, they can develop shingles later, he said.
The other suggests that the reaction, the response of the body to the virus ended up causing harm in the process, a form of collateral damage, said Krumholz. "It was friendly fire, your body was going up against the invader, the virus, but in the course of going after the invade, it ended up overshooting and developing a way of responding that ended up injuring the body itself," he said.
Once that process begins, it's difficult to slow it down, he added.
There are other instances where that sort of thing can happen, he said. "The immune system can be our best friend and it can be our worst enemy."
While the virus might not have sentience, it is smart, and has learned tactics to evade the body's immune system, such as camouflage. Then the immune system can start attacking itself in its effort to seek out the invader.
"They know how to survive," he said.