Among the many confounding aspects of the coronavirus is the spectrum of possible symptoms, as well as their severity and duration. Some people develop mild illness and recover quickly, with no lasting effects. But studies estimate that 10 to 30 percent of people report persistent or new medical issues months after their initial coronavirus infections — a constellation of symptoms known as long Covid. People who experience mild or moderate illness, as well as those without any underlying medical conditions, can nonetheless experience some debilitating long-term symptoms, including fatigue, shortness of breath, an erratic heart rate, headaches, dizziness, depression and problems with memory and concentration.
Such lingering medical issues are so varied that one study by a patient-led research group evaluated 203 symptoms that may fluctuate or even appear out of the blue after people seem to have recovered.
As Dr. Ziyad Al-Aly, the chief of research and development at the VA St. Louis Healthcare System and a clinical epidemiologist at Washington University in St. Louis, said, “If you’ve seen one patient with long Covid, you’ve seen one patient with long Covid.”
There is little consensus on the exact definition of long Covid, also known by the medical term PASC, or post-acute sequelae of Covid-19. While the World Health Organization says long Covid starts three months after the original bout of illness or positive test result, the Centers for Disease Control and Prevention sets the timeline at just after one month.