Long COVID is a term used to describe a wide variety of health problems that some people experience after an infection of SARS-CoV-2. The most commonly reported symptom of long COVID is fatigue, especially after physical or mental effort. Others report a variety of symptoms including shortness of breath, cough, chest pain, heart palpitations, difficulty concentrating, headache, sleep problems, lightheadedness, changes in small or taste, changes in digestive system, and joint pain.
Researchers at Cedars-Sinai Medical Center have proposed a theory for why some people infected with SARS-CoV-2 go on to be affected by long COVID. The researchers hypothesize that a specific region of the COVID virus, residues E661-R685, promotes hyperinflammation and leads to the resulting long COVID symptoms. This hypothesis is based on a series of computational analyses of SARS-CoV-2 sequence, structure and interactions, along with RNA sequencing and analysis.
Residues E661-R685 are a stretch of amino acids that make up a single part of the spike proteins that allow SARS-CoV-2 to latch onto cells and cause infection. Due to the molecular structure and functionality of these residues, the researchers believe that these spike proteins can cross the blood-brain barrier, resulting in damaged brain cells.
Since this research is still speculative, the researchers involved are calling on the scientific community to investigate this region of COVID. Magali Noval Rivas, PhD, a Cedars-Sinai researcher who authored the paper, says that “we need to conduct more research to prove if this is indeed the mechanism that causes long COVID so that we can develop treatments to block it.”
Though the cause of long COVID is not yet known for certain, researchers have identified multiple risk factors for developing long COVID. Individuals who were hospitalized, needed intensive care, and experienced more severe cases of COVID are at a higher risk of developing long COVID.
People who have not been vaccinated for COVID are both more likely to develop a severe case of COVID and more likely to develop long COVID. Among patients who are hospitalized for COVID, more than 30% experience long COVID at 6 months post-infection compared to less than 2.5% among those who were not hospitalized.
Sources: Centers for Disease Control and Prevention, Frontiers in Immunology