(CNN) It's been almost a year since Michael Reagan, 50, came down with Covid-19.
"I woke up first thing in the morning and I felt really hot and out of breath," he said, recalling the morning of March 22, 2020. "I went into the bathroom trying to catch my breath, and I immediately coughed up blood into the sink. ... I ended up in the hospital that day and tested positive for Covid."
Reagan said he spent two months in and out of the hospital last spring, with acute Covid-19.
But for as hard as that was, what he's been through since could be considered just as bad, if not worse: His current symptoms include constant pain in his chest, painful nerve pain in his hands and legs, seizures, tremors, and the loss of vision in one eye.
"Since then it has been a roller coaster," he said, with ups and downs, new symptoms, a whole series of doctors, medications and tests.
"I realized that I have a lot of damage from Covid and it's changed my life completely," he said. He has not been able to return to anything near the active life he enjoyed before.
Unlike Reagan, when 34-year-old Stephanie Condra got sick with Covid-19 last summer, she didn't have to be hospitalized. Her symptoms were comparatively mild: fatigue, shortness of breath, stomach pain and cramping, and a low-grade fever.
But, after it appeared she had recovered from her acute illness, Condra says she began developing a wide array of health problems that that waxed and waned but did not clear up: terrible sinus pain, nausea and loss of appetite, bone-crushing fatigue, dizziness, a burning sensation in her chest, a dry cough, brain fog, confusion, concentration issues and problems with word retrieval.
"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," she explained.
While Condra said she started getting better at the beginning of 2021, she describes her progress as slow and halting. "I'm really only able to function for maybe, tops, like four hours during a day," she said.
More than a year into the pandemic, what has become abundantly clear is that SARS-CoV-2 -- the virus that causes Covid-19 -- is a tricky virus: Some people aren't aware they're infected at all, while others are hospitalized and some die. And a growing group of people get sick and then never fully recover. In support groups, they sometimes refer to themselves as long-haulers; their condition is alternately called long Covid, continued Covid, post-Covid syndrome or post-acute Covid syndrome.
Nobody is sure what percentage of people who've been infected with SARS-CoV-2 go on to develop post-Covid syndrome.
A new research letter published Friday in the journal JAMA Network Open is shedding new light on the condition. Researchers from the University of Washington followed 177 people with laboratory-confirmed SARS-CoV-2 infection for up to nine months -- the longest follow-up to date. Notably, this group included 150 outpatients, who had "mild" disease and were not hospitalized.
They found that 30% of respondents reported persistent symptoms. The most common were fatigue and loss of smell or taste. More than 30% of respondents reported worse quality of life compared to before getting sick. And 14 participants (8%) -- including 9 people who had not been hospitalized -- reported having trouble performing at least one usual activity, such as daily chores.
The researchers wrote that with 57.8 million cases worldwide, "even a small incidence of long-term debility could have enormous health and economic consequences." There are now more than 110 million cases worldwide, according to the latest data compiled by Johns Hopkins University.
A much larger study, published in early January in The Lancet, found that of 1,733 coronavirus patients treated in the Chinese city of Wuhan, 76% were still experiencing at least one symptom six months after their symptoms began. But this group was made up entirely of hospitalized patients.
The Center for Post-Covid Care at Mount Sinai Health System, in New York City, was the first of its kind to open back up in May. So far, the center has seen more than 1600 patients -- including Reagan and Condra -- and there's a months-long wait to get an appointment.
"It's very hard to predict who will get these symptoms," Dr. Zijian Chen, the medical director, told me when I interviewed him last summer. "The patients we're seeing at the center are, you know, of all races. They span in age from the 20s to 70s and 80s. You have patients who are both male and female, of equal distribution."
He said having mild illness or being healthy to begin with, is no protection from having persistent symptoms.
"I would presume that if ... you had a pre-existing condition, that the infection with the virus can worsen that condition. But again, we're also seeing patients who are previously healthy, had somewhat relatively mild illness," Chen said.
Age, he said, isn't a predictor either.
Another baffling aspect of post-Covid syndrome is the vast and seemingly random array of health issues that some patients face.
Dr. Christian Sandrock is a professor of medicine in pulmonary critical care and infectious diseases at UC Davis School of Medicine, in Sacramento, California. As director of critical care, he is one of the doctors who assesses patients at UC Davis' Post-COVID-19 Clinic. It was the first such center in the region to open its doors, back in October.
"When we look at the long-term symptoms ... the big things we see are fatigue, lethargy and sleep disturbance, and that makes up probably more than half of what we see. Loss of taste and smell is a very specific one that we will see. Shortness of breath is a very specific one, and chest pain as well," he said. Many patients have multiple symptoms, and the symptoms can come and go.
Sandrock categorizes the symptoms into several buckets. Problems such as chest pain, shortness of breath and heart inflammation fall into the cardiovascular category. Chest pain and shortness of breath could, depending on the underlying cause, fall into the respiratory category, as does decreased exercise tolerance and pulmonary function abnormalities. He puts rashes, hair loss and even tooth loss into the dermatologic category. Fatigue, brain fog and not feeling like oneself belong to the constitutional category. The neurological category comprises loss of smell and taste, sleep dysregulation, altered cognition and memory impairment. Depression, anxiety and mood changes, he explained, all fall into the psychiatric category.
As for what is causing those symptoms, Sandrock points to several culprits. Some might be caused by the complications of an extended hospital or ICU stay, which is known to be hard on the body and have lasting effects. Some could be triggered by microvascular disease -- damage to the capillaries, which Sandrock says is behind many symptoms, from chest pain to "Covid toes" to fatigue and even brain fog. Some symptoms could be set off by an autoimmune response triggered by high levels of inflammation, such as joint and body aches, sleep disturbances, depression and fatigue. And some could be as a direct infection by the virus, such as loss of smell and/or taste, according to Sandrock.
Treatment, Sandrock said, is very much individualized and depends on the symptoms and the underlying cause of those symptoms.
"Treatment needs to be customized," he said. "We have to really spend our time seeing what our patients need. Some of them -- they really just have chest pain, shortness of breath and low oxygen levels, and in that case we can manage that. Another person may have a lot of brain fog, difficulty concentrating and sleep disturbances -- that's a whole host of other things we then need to do."
It can involve referral to other experts within the clinic, medications and rehabilitation. Medications such as immune-modulators, anti-inflammatories, anti-depressants, beta-blockers and/or steroids, he said. Rehab, such as cognitive, pulmonary and/or cardiac rehab. Sleep studies to root out the cause of any sleep disturbance.
But there is one constant. "The only treatment I've seen that's consistent is a lot of what we would call supportive care. So that really involves better living and higher quality living, for lack of a better term. But that means you really need sleep. Sleep is going to matter a lot," Sandrock said, noting that stress reduction, meditation and yoga are also part of the mix.
He said patients need to adjust their life to a less stressful and slower pace to allow the body to heal. "So, we want people to really be patient with themselves, know that it's going to take a lot of time as they work through it. So that, I think, is key," he said.
Dr. Dayna McCarthy, a team member at Mount Sinai's Center for Post-Covid Care, agrees patients have to adjust their expectations of themselves and slow down.
"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," she said.
Improvements are hard-won and extremely slow. "Day to day it's really hard to measure those improvements. As these symptoms wax and wane, the improvement is very stuttering. You know, three steps forward, two steps back," said Sandrock, noting that he measures improvements in terms of months.
McCarthy, who calls the process "glacially slow," says patients do get better with supportive care and time. "But a lot of it falls on the patient and having to understand and come to terms with the fact that their life needs to change for them to get better," she said. "And when you're young and healthy and you're used to being in kind of fifth gear -- you're 'full steam ahead' and now we're telling you, you really have to kind of shift back and shift down to allow your body what it needs to recuperate and recover. [It's] a very difficult thing for patients to process and embrace," she said.
Both Sandrock and McCarthy say much more research is needed to better understand post-Covid syndrome, including who gets it and best treatment practices. But they're optimistic about the future, now that the condition has been recognized and "science is getting behind it," as McCarthy put it.
"So, people are coming together both in systems, and then systems coming together nationally, and then internationally. So, there's been this mass collaboration of scientists and health care professionals that are looking for answers. And that takes time. But I'm very happy to report that," she said.
Sandrock said he was excited to learn that the National Institutes of Health recently announced it would be offering research grants as part of its "Post-Acute Sequelae of SARS-CoV-2 Infection (PASC)" initiative.
As for Michael Reagan and Stephanie Condra, they're carrying on as best they can.
"Every day I make the conscious decision to be optimistic and to be positive. I can't always control what circumstances life throws at me, but I can control how I carry myself. If I carry myself with grace and dignity that I'm going to be OK," Reagan said. "I have a very supportive family. I have a supportive partner. I have job [and] coworkers that understand. I have excellent doctors. So, I try to look at things I am grateful for."
Said Condra, "I really had to relinquish my sense of control in not knowing when this is going to end for me. But really being grateful for the improvements that are happening, and at least [getting] back some level of having a quality of life and being able to take advantage of the days, the weeks where I am feeling better ... but it's mind-blowing that it's been so long."