Sioux City, Iowa (CNN) -- COVID-19 has been a part of our lives for about a year, but we're still learning about its long-term effects on the body.
According to the Mayo Clinic, people who continue to experience symptoms after their recovery refer to themselves as "long haulers."
Older people and those with serious health conditions are likely to experience the lingering symptoms such as fatigue, shortness of breath, a cough, joint pain and chest pain.
A new study suggests even people who have mild cases of the virus, may feel some symptoms months later.
Most COVID-19 cases are symptomatic, mild or moderate, but even in those cases, the Coronavirus can have lasting effects, even months later.
"My symptoms are constantly evolving. I get the same symptoms again and again, and it's like one will kind of disappear and then others will come up," said Stephanie Condra.
More than a year into the pandemic, there's still a lot we don't know about the virus and how it affects those who get it.
However, a new research letter published in the Journal Jama Network Open indicates 30% of more than 175 COVID patients the group researched, most of whom had mild symptoms and no hospitalization, still had persistent symptoms, up to nine months later. The most common symptoms were fatigue and loss of smell or taste.
Dr. Dayna McCarthy, Mount Sinai's Center for Post-COVID Care, said, "We're like rubber bands. We just want to kind of snap back to the way that we were before. So, I think that has been one of the biggest challenges. But if people are not able to do that, and they keep pushing, that is when the symptoms just do not get better."
Dr. McCarthy works with those suffering from post-COVID symptoms, at the Center For Post-COVID-Care at Mount Sinai Health System in New York. She says a majority of her patients are in their 20s to 50s, and with time and care, the symptoms recede.
"We are seeing patients get better. It's just glacially slow," said Dr. McCarthy.
Dr. McCarthy says much more research is needed to better understand Post-COVID Syndrome, including a better understanding of who gets it and how to best treat those patients.
Dr. McCarthy says there has been a mass collaboration of scientists and health care professionals, who are looking for answers into Post-COVID Syndrome, but she says it takes time.