Six local hospitals are joining a national effort to solve the mysteries of what is called “long COVID-19.”Cassandra Cast hopes her struggles with exhaustion and memory can help.”I use a cane now to steady myself,” she said. “And I’m only 57.”It’s been two years since Cast had a severe case of COVID-19 in the hospital. At one point, doctors inserted a tube in her trachea to help her breathe.”It was horrible,” she said. “My kidneys started to fail twice.”Doctors told her three kids that she might not make it. For weeks, they worried their mom would die from COVID-19 — just like Cast’s mom had a few months earlier.”That was devastating,” Cast said. “She went into the hospital on a Wednesday. She was gone on a Monday morning. We couldn’t say goodbye to her. So that was a lot.”Cast survived her case of COVID-19. Doctors now say she’s recovered, even though her body still tells her that she has not.”I can go from here to my bedroom in the next room and be out of breath,” she said. “Taking a shower sometimes will knock me out for the entire day.”Cast’s complaints are similar to what doctors have been hearing from patients since the early days of the pandemic. Weeks or sometimes months after the virus should have moved on, they’re still experiencing pain, headaches, fatigue, shortness of breath, depression, even brain fog.”This is a real syndrome that many patients are suffering from,” said Dr. Bruce Levy, chief of the pulmonary division at Brigham and Women’s Hospital who is now leading Boston’s effort to recruit more than 900 COVID-19 survivors and patients for a national study.The goal is to figure out why COVID-19 appears to linger in the body when many other viruses don’t.”Even influenza or some of the more severe viruses that we typically encounter, people generally recover within a month,” Levy said. “And for COVID, many people were having symptoms that persisted long after 30 days from their infection.”The symptoms of long COVID-19 appear to go well beyond the lungs. That’s why the research team now includes experts in the heart, brain, joints and nervous system.”Perhaps as this virus finds entry into the respiratory tract, it’s also finding entry into other parts of the body,” Levy said. “It’s very jarring for patients.”Cast hopes the study’s results will lead to treatments — and then finally, relief.”I’m not the same person I was,” she said. “It’s hard to grapple with that, but that’s the key. You’re not that same person.”Nationally, researchers hope to recruit about 20,000 adults and 20,000 children for the study.To learn more about enrolling, click here.