When the novel coronavirus enters your body—primarily through the nose or mouth—it travels down your respiratory tract, infecting your body’s cells along the way before reaching your lungs. Then, according to Science magazine, your lungs swell as your immune system’s white blood cells release inflammatory molecules called chemokines. These chemokines help fight infected cells, but in turn, disrupt healthy oxygen transfer. And depending on the severity of the swelling, this process can lead to a build-up of fluid and dead cells, causing significant damage to your lungs—not all of which goes away after you fight off the infection. In fact, doctors in Hong Kong told the South China Morning Post that some coronavirus survivors have a “20 to 30 percent drop in lung function” even after recovery. So what exactly goes on? “Researchers have found that long-term scarring of the lungs, known as fibrosis, can be a problem, which could cause varying levels of long-term breathing impairments,” Ari Bernstein, MD, advisor for Fruit Street Health and CovidMD, previously told Best Life. In severe cases of COVID-19, that long-term scarring may be the result of a complication known as acute respiratory distress syndrome (ARDS), writes Panagis Galiatsatos, MD, MHS, an expert on lung disease at Johns Hopkins Bayview Medical Center.ae0fcc31ae342fd3a1346ebb1f342fcb A form of lung failure, ARDS causes your air sacs to become filled with fluid leaking from surrounding blood vessels in the lungs, preventing you from being able to breathe. Galiatsatos, who treats patients with COVID-19, notes that ARDS—which is often the result of coronavirus-induced pneumonia—can be fatal, and when it isn’t, patients often have long-lasting pulmonary scarring. The good news is, that scarring is not necessarily irreversible, Galiatsatos says. “Recovery from lung damage takes time,” he notes. “There’s the initial injury to the lungs, followed by scarring. Over time, the tissue heals, but it can take three months to a year or more for a person’s lung function to return to pre-COVID-19 levels.” There is still much to be learned about the lasting impact the coronavirus can have on survivors, but when it comes to the lungs, Galiatsatos says patients should expect to undergo additional treatment. “Once the pandemic is over, there will be a group of patients with new health needs: the survivors,” he writes. “Doctors, respiratory therapists, and other health care providers will need to help these patients recover their lung function as much as possible.” And for more information on developing a defense against COVID-19, check out This One Common Ailment Could Boost Your Coronavirus Immunity.