Doctors say that at least 10% of those who become infected with COVID-19 will develop long-haul symptoms that can range from relatively mild to much more severe. One national research group is trying to find out why people develop these long-haul symptoms."This isn't a condition in which you can push through and try to get rid of the symptoms through exercising or anything like that," said Dr. Ashok Gupta, COVID-19 long-haul researcher.Gupta monitors the effects of COVID-19 and lingering symptoms."It's very difficult. What's actually causing the long COVID because it's happening in patients who have a very severe illness or are hospitalized, right through to people with very mild illness," he said.Gupta said that some COVID-19 long-haul cases can cause responsive changes in the brain."Initially, you may have a normal immune response to the COVID-19 infection. The infection goes away but the brain stays stuck. It still believes that the infection is present because of the severity of the infection," he said.Gupta said that is why some people are experiencing long COVID-19."We get ongoing symptoms, where the body is essentially fighting a ghost virus that it thinks is still present in the body," he said.Gupta said that neuroplasticity works in a similar way with folks who've had an amputation."It's very similar to phantom limb pain," he said.Gupta treats patients with chronic illnesses but since COVID-19, he said people are confusing long-haul symptoms and chronic illness."The hope is that people don't feel depressed and anxious about their long-COVID symptoms but realize people do get better," he said.Gupta said that ultimately it is about rest, getting a lot of it and avoiding stress.The doctor said that as many as 20% percent of children who have gotten COVID-19 are dealing with some short and long-term effects from six to eight weeks after the original infection.