Virus World

A picture is emerging of the toll long Covid takes inside the body and why it can be so debilitating.  Millions of people continue to suffer from exhaustion, cognitive problems and other long-lasting symptoms after a coronavirus infection. The exact causes of the illness, known as long Covid, are not known. But new research offers clues, describing the toll the illness takes on the body and why it can be so debilitating.

Diagnosing Long Covid

Patients with severe Covid may wind up in hospitals or on ventilators until their symptoms resolve. Damage to the body from severe Covid — pneumonia, low oxygen, inflammation — typically shows up on traditional diagnostic tests. Long Covid is different: A chronic illness with a wide variety of symptoms, many of which are not explainable using conventional lab tests. Difficulties in detecting the illness have led some doctors to dismiss patients, or to misdiagnose their symptoms as psychosomatic. But researchers looking more deeply at long Covid patients have found visible dysfunction throughout the body. Studies estimate that perhaps 10 to 30 percent of people infected with the coronavirus may develop long-term symptoms. It’s unclear why some people develop long Covid and others don’t, but four factors appear to increase the risk: high levels of viral RNA early during an infection, the presence of certain autoantibodies, the reactivation of Epstein-Barr virus and having Type 2 diabetes.

The Immune System

“Dang, why am I always so sick?” — Messiah Rodriguez, 17 Long Covid patients appear to have disrupted immune systems compared to post-Covid patients who fully recover. Many researchers believe chronic immune dysfunction after a coronavirus infection may set off a chain of symptoms throughout the body. One possibility is that the body is still fighting remnants of the coronavirus. Researchers found that the virus spreads widely during an initial infection, and that viral genetic material can remain embedded in tissues — in the intestines, lymph nodes and elsewhere — for many months. Ongoing studies are trying to determine if these viral reservoirs cause inflammation in surrounding tissues, which could lead to brain fog, gastrointestinal problems and other symptoms.  Researchers have also found evidence that Covid may trigger a lasting and damaging autoimmune response. Studies have found surprisingly high levels of autoantibodies, which mistakenly attack a patient’s own tissues, many months after an initial infection. A third possibility is that the initial viral infection triggers chronic inflammation, possibly by reactivating other viruses in the patient’s body that are normally dormant. The reactivation of Epstein-Barr virus, which infects most people when they are young, might help predict whether a person will develop long Covid, one study found. Inside the intricate world of the immune system, these explanations may coexist. And just as different long Covid patients may have different symptoms, they may also have different immune problems, too. Identifying the problems that are central to each patient’s illness will be critical for guiding treatment, said Dr. Akiko Iwasaki, an immunologist at Yale.

For instance, a patient with autoantibodies might benefit from immunosuppressive medication, while a patient with remnants of the Covid virus should receive antivirals, Dr. Iwasaki said. “Depending on what each person has, the treatment would be quite different.”

The Circulatory System

“Something as simple as climbing on a ladder all of a sudden became a mountain.” — Eddie Palacios, 50

Many long Covid patients struggle with physical activity long after their initial infection, and experience a relapse of symptoms if they exercise. Initial studies suggest that dysfunction in the circulatory system might impair the flow of oxygen to muscles and other tissues, limiting aerobic capacity and causing severe fatigue. In one study, patients with long-lasting Covid symptoms had unexpected responses to riding a bike. Despite having apparently normal hearts and lungs, their muscles were only able to extract a portion of the normal amount of oxygen from small blood vessels as they pedaled, markedly reducing their exercise capacity. One possible culprit: Chronic inflammation may damage nerve fibers that help control circulation, a condition called small fiber neuropathy. The damaged fibers, seen in skin biopsies, are associated with dysautonomia, a malfunction of automatic functions like heart rate, breathing and digestion that is very common in long Covid patients.  These findings demonstrate that people with long Covid are suffering systemic physical problems, rather than just being anxious or out of shape, said Dr. David M. Systrom, an exercise physiologist at Brigham and Women’s Hospital who helped conduct the bike study. “You can’t make up small fiber neuropathy by skin biopsy. That isn’t in somebody’s head,” Dr. Systrom said. “You can’t make up poor oxygen extraction to this degree. All of these are objective measures of disease.” South African researchers found another circulation problem: Microscopic blood clots. Tiny clots that form during an initial Covid infection will typically break down naturally, but might persist in long Covid patients. These clots could block the tiny capillaries that carry oxygen to tissues throughout the body..... 

Though the number of new deaths has been curving downward, the virus continues to circulate widely within the United States. As states move to partly reopen their economies, thousands of new cases are still being identified each day and true normalcy remains a distant vision. Every day, more beloved events are scrubbed from the calendar. There will be no Made in Hawaii Festival, no Algonquin Founders’ Days in Illinois, no Christmas poinsettia sale at Duarte Nursery in California.

These states have had recent growth in newly reported cases over the last 14 days, in part because some have recently ramped up their testing capacity. The White House released criteria for states to reopen based on a “downward trajectory” of cases over the last 14 days, though it did not define how to measure the trajectory. Scales are adjusted for each state to make the curve more readable.