TORONTO -- A growing body of evidence indicates that long-term “ongoing” COVID-19 may not be a single syndrome but possibly up to four different syndromes, according to a new review by the National Institute for Health Research, a U.K. government agency.

The virus can affect numerous other organs and systems beyond the lungs and respiratory system; patients experiencing the long-term effects of the virus, often for weeks and months after the initial infection, have reported a wide range of fluctuating symptoms affecting the brain, the cardiovascular system and heart, kidneys, gut, liver and even skin.

The NIHR review, Living with COVID-19, found that in many cases, patients experienced symptoms in one physiological system, saw them ebb, only to appear in another system. All of these symptoms poses a diagnostic challenge for medical professionals, the report said.

Drawing on published studies and interviews with long-term COVID patients, one of the key early conclusions in the review is that long-term COVID-19 could be due to multiple syndromes including:

  • Post-Intensive Care syndrome
  • Post Viral Fatigue syndrome
  • Long-Term COVID syndrome
  • Permanent organ damage

A recent study found that more than half of recovered patients that were examined had reported crippling fatigue-- post-viral fatigue syndrome -- even months after recovery. At least one study found that among 100 adults who recovered from the coronavirus, 60 per cent had ongoing inflammation in the heart.

The NIHR review aims to gather ongoing evidence on long-haulers, which number at least in the tens of thousands, if not significantly more, in order to build a clearer framework for diagnosing patients. This would help health-care providers, researchers and policymakers understand patients who suffer from the disease, provide better access, better COVID care, and inform long-term planning around what additional services are needed for patients.

“The changing and multiple symptoms of ongoing COVID-19 are not well served by the way healthcare is currently organized,” author Dr. Elaine Maxwell wrote in the review. “COVID-19 is a multisystem disease and people’s experience echoes the challenges already experienced by people with multiple comorbidities, who experience limited service integration.”

Findings from the focus group in the review noted that patients who had been on ventilation and in critical care had ongoing needs that were similar to those who did not receive any hospital care.

In some cases, the effects of COVID-19 can trigger other health events, such as a stroke, or loss of muscle tone, which are not due to the virus itself, but still require specialized care.


The attention placed on acute respiratory symptoms and the perception that recovery after two weeks is the norm, however, often means patients who were not hospitalized or formally diagnosed may be overlooked or dismissed altogether by skeptical health-care professionals, despite potentially debilitating symptoms, the report found.

“It’s a crafty illness, and it’s a doubting illness because it makes you doubt yourself and it makes people doubt you,” one focus group patient said in the review.

Some health professionals have suggested to patients that their symptoms were due to anxiety, despite the patient’s conviction the symptoms were in fact causing the anxiety.

“A number of people said there were occasions when they thought they might not survive the night and there was anger at being labelled ‘mild cases’ simply because they didn’t access respiratory support in hospitals,” Maxwell wrote.

In Canada, an online group called COVID Long Haulers Support Group Canada has more than 2,800 members and is growing. The group has asked the federal and provincial governments to promise more help for those who develop disabling neurological COVID symptoms.


The review also documented the unpredictable nature of the virus through its focus group. For some patients, the first symptoms were not a cough, fever, or a shortness of breath. For others, more serious symptoms appeared only weeks into their illness.

“I first had symptoms on 5th March but it wasn’t until mid-May my heart symptoms came on and they were the most frightening of all,” one patient said.

“It’s a roller coaster rather than an incline, I’m going up and down and up and down. If I do too much I feel worse, and if I don’t do enough I feel worse and so when I feel better I have to bank the energy,” another patient reported.

Still, Maxwell notes that numerous questions remain unanswered from a medical, healthcare, and socioeconomic perspective. Going forward, the NIHR plans to update the review on an ongoing basis and include marginalized voices like the homeless and those in prison to draw a more complete picture of the disease’s impact.