Hospitals and medical groups have created specialized post-COVID care clinics to treat these “long haulers” and better understand the mysterious illness.

Here are seven learnings doctors working in long-COVID clinics want you to know:

The cause of long COVID is still unclear

While it’s clear that a SARS-CoV-2 infection is the trigger for long COVID, little else about the condition that affects between 10% and 80% of those diagnosed with COVID is well understood.

Researchers have put forth several theories: One study suggested that the coronavirus might reactivate latent viruses, including the Epstein-Barr virus, causing long-term symptoms, and another indicated that an ineffective immune response to COVID failed to trigger the antibodies needed to fight the infection, leading to lingering symptoms.

Regardless of the cause, researchers do agree on one thing: Long COVID is not a lingering COVID infection.

“This is a whole new syndrome, a whole new disease,” explains Dr. Rany Condos, director of the Post-COVID Program at NYU Langone Health.

More severe infection heightens the risk

Patients with long COVID tend to fall into three categories: those who never recovered after their initial infection; those who developed long-COVID symptoms following COVID-related hospitalization; and those who experienced symptoms after their recovery from the initial infection.

Among those groups, there appears to be a connection between the severity of the initial infection and the risk of becoming a long hauler.

“Folks who were hospitalized, in the intensive care unit, on ventilators, have identifiable organ and tissue damage and very different courses [of long COVID] than folks who were never hospitalized in the first place,” says Dr. Kristin Englund, director of the ReCOVer Clinic at Cleveland Clinic.

But that doesn’t mean those who had mild infections are risk-free. In fact, Englund estimates that 80% of the patients receiving treatment at the ReCOVer Clinic were never hospitalized. Dr. Benjamin Abramoff, director of the Post-COVID Assessment and Recovery Clinic at Penn Medicine, is seeing a similar pattern.

Vaccination offers some protection

A study of 13 million people found that those who received the COVID vaccine were 15% less likely to develop long COVID than those who were unvaccinated; smaller studies have shown that those who received two doses of the COVID vaccine cut their risk of developing long COVID in half.

“The vaccine is protective against getting COVID or getting critically ill in the first place, and that protects you from getting the long-term symptoms,” Abramoff says.

Research is ongoing

The National Institutes of Health launched the RECOVER Initiative, a $1.15 billion project to research long COVID, and hundreds of clinical trials are recruiting long haulers to better understand the condition and possible treatments.

But clinical research takes time. Englund believes it could be “several years” before we understand the condition, adding, “Nobody has the answer to long COVID right now.”

Delaying treatment affects recovery

The latest data shows that long-COVID symptoms lasted an average of 14.8 months among patients who were not hospitalized for COVID, with some patients experiencing long-COVID symptoms for 18 months following their initial COVID infection.

While there is no cure for long COVID, it’s still important to seek a diagnosis and treatment.

“We’re able to at least help symptomatically, to help patients get better,” Englund says. “Patients who delay coming in are suffering for a longer period of time, and it certainly delays the road to recovery.”

Long-COVID treatment centers can help

Long-COVID centers have been set up in 48 states and are staffed with multidisciplinary health care teams to help long haulers manage their symptoms.

“By coming into the clinic and being evaluated and making sure that there is nothing that we’re missing makes a difference in how patients feel,” Condos says. “There’s great value in coming in [to a long-COVID clinic] to discuss symptoms and to be validated and told that we do see these symptoms in patients after they get COVID, and it will get better.”

Long-COVID treatment scams abound

The list of COVID scams is long, and there are a myriad of companies promising to help diagnose and treat the condition with blood tests, special diets, cocktails of supplements, breathing exercises, and oxygen chambers. The problem: There is no science to support these so-called miracle treatments, according to Englund.

“People are desperate [and] may fall prey to the number of treatments that are advertised that are going to be potentially expensive and not helpful at all—or potentially harmful,” Englund says. “If it sounds too good to be true, it probably is.”