Watch: A New York City Doctor Warns of COVID-19’s Long-Term Effects

Most people who are infected with COVID-19 ultimately survive. But for many patients, that may mean living with life-altering symptoms that linger—or become permanent.

In a conversation with Katie Couric for TIME, Dr. Rony Shimony, a cardiologist at Mount Sinai Hospital in New York, said he and his colleagues have noticed that patients as young as their 30s who survived COVID-19 are reporting lasting symptoms. Doctors have discovered issues including kidney damage, reduction in heart function, and cognitive impairment in patients who had been infected with COVID-19, Shimony said, adding that the sicker the patients had been from COVID-19, the greater the damage to their organs.

“We’re now beginning to understand the impact on the brain, on the heart, on the lungs, on the kidneys,” Shimony said. “This particular infection is involving all the body. We need to really take time to understand further the impact on it. And it really causes us to be more cautious about what’s coming ahead.”

History raises further cause for concern. After the Spanish flu of 1918, Shimony said as many as 50% to 60% of patients were found to still have effects four years later. He expects we will see a similar effect with COVID-19.

Fortunately, scientists and doctors are learning about how to treat patients with the disease, including the importance of starting treatment early to head off the risk of organ damage, Shimony said. However, the risk of long-term effects means it’s vital to prevent the disease from spreading.

“This is a disease that can leave people disabled for years to come, or a lifetime,” Shimony said. “The impact it has on a family, psychologically, financially, et cetera, that’s an impact for the country. So we have to build up prevention. We have to listen to the experts. Wear the mask and the social distancing.”

This interview is part of a special series produced in collaboration with Katie Couric. Read more from TIME Reports with Katie Couric, and sign up for her weekday morning newsletter Wake-Up Call with Katie Couric.