Long COVID-19 is not wholly understood, but new research is shedding some light and helping with plausible theories.

Long COVID-19 continues to puzzle physicians, but more answers are being acquired thanks to research and the general passing of time. A new study could explain why some people experience long COVID-19 while others don’t.

The study, published in the journal Neurology: Neuroimmunology & Neuroinflammation, was conducted on a small group of just 17 subjects, and found that symptoms of long COVID-19 can be influenced by nerve damage.

RELATED: 30 Minutes Of Weight Training Can Reduce Your Risk Of These Diseases

Researchers found that 10 of the patients suffered from peripheral neuropathy, a condition that results in weakness and pain in the extremities due to nerve damage, usually presented on the hands and feet.

“What we asked is, could some of what’s going on with long-haul COVID actually reflect an undiagnosed peripheral neuropathy?” said Anne Louise Oaklander, associate professor at Harvard and leader of the research team. “That’s really point one: We found a real objective medical problem in over half of these patients.”

Long COVID-19 expresses itself in a variety of ways, ranging from symptoms like fatigue and brain fog, to trouble breathing, lingering coughs, joint pain, chest pain, and more. It’s a debilitating condition that’s not thoroughly understood and thus not yet able to be diagnosed. It can affect anyone who suffered from a COVID-19 infection, with the severity of the disease often correlated with the appearance of these symptoms in the long term.

While this study shows some compelling evidence that could help physicians in the future, researchers warn that it’s important to take things one step at a time and not jump to any conclusions just yet. This study was based on a very small sample of subjects, who were already diagnosed with a neurological condition.

RELATED: This Is How Prevalent Hair Loss Is For Women Post-Menopause

For now, researchers hope to find a way to determine how to better understand long COVID-19 by learning who is more at risk. A previous study, published in the journal Nature, found that people with long COVID-19 tended to have lower antibodies post COVID-19 infection than others. “These individuals might have a disadvantage from the start,” said the lead researcher. “And then due to their asthmatic background, they might also react slightly differently to viruses, which then leads to a misguided immune response.”