A new study found that more than half of recovering COVID-19 patients had tissue irregularities in their organs months after infection. The researchers studied patients who were admitted to Oxford University Hospitals National Health Service Foundation in the U.K. between March and May and found that months later, 60% of the patients had abnormalities on their lungs, 64% had breathing issues, and 55% still suffered from fatigue.

According to Medical Daily, of the 31% who showed acute liver damage upon admission, 10% still had persistent liver impairment two to three months later. The study revealed that while COVID-19 is considered to be a respiratory disease, it damages the tissues of several organs.

“On MRI, tissue signal abnormalities were seen in the lungs (60%), heart (26%), liver (10%) and kidneys (29%) of patients,” the authors wrote. They theorized that the strong inflammatory response of the immune system to beat the infection triggers tissue damage.

Other researchers have reported similar findings. A study published last July in Brain, a neurological journal, found preliminary clinical data that COVID-19 infection is associated with neurological and neuropsychiatric illness. According to The National Interest, the virus starves cells of life-giving oxygen, causing them to wither and die. For some individuals, this can be deadly.

“If the brain becomes infected, it could have a lethal consequence,” Dr. Akiko Iwasaki, lead author of the study, said. While most of the data says that SARS-CoV-2, the virus that causes COVID-19, primarily attacks the lungs, according to The New York Times, half of the patients report neurological symptoms such as headaches, confusion and delirium.

A study published by Ohio state University found that four out of 26 competitive athletes who had COVID-19 developed symptoms of myocarditis, a disease which affects the heart muscle and can cause heart failure or sudden death, according to USA Today.

As many as one-third of COVID-19 victims develop lingering symptoms. These so-called “long haulers” suffer symptoms ranging from chest pain and fatigue to heart irregularities. Some victims are unable to return to work and may require long-term medical care, according to The New York Times. The new study may shed light on why some people become long haulers.

“It is believed that there are many organs of the body that are affected by the virus,” said Chris Glembotski, Ph.D., a renowned researcher in cardiovascular disease at the University of Arizona, according to USA Today. “After infection, the virus goes to different organs and tissues and after entering them causes an inflammation response.”