Common symptoms for COVID-19 are fever, cough, shortness of breath, fatigue and loss of taste or smell, according to the Centers for Disease Control and Prevention. But new research found that delirium coupled with fever can be an early sign of the disease.

According to Eat This, Not That!, researcher Javier Correa, of the Universitat Oberta de Catalunya in Barcelona, Spain, said that delirium ''is a state of confusion in which the person feels out of touch with reality, as if they are dreaming.'' He added that if someone appears to be suddenly confused, it may be a sign of infection. Correa and other UOC colleagues focused on how the coronavirus affects the brain and central nervous system, producing not only delirium but also psychotic episodes.

He boiled down his hypotheses into three possible scenarios. One, that the brain does not receive enough oxygen which leads to hypoxia, and secondly that the virus causes inflammation in brain tissue. The third possible cause of delirium could be that the virus passes directly through the blood-brain barrier and attacks the brain directly. Correa said that based on the autopsies of COVID-19 victims, systemic inflammation, along with lack of oxygen to the brain, most likely trigger delirium.

Yale University researchers previously found that the coronavirus enters brain cells directly and replicates itself, causing the neurological symptoms some patients have experienced. The researchers discovered this unique ability by analyzing coronavirus infections in mouse models, brain cells in lab dishes, and brain tissue in deceased COVID-19 positive patients.

According to The National Interest, the pathogen also starves nearby 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 say 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.