As researchers work to understand both the short and long-term effects of the novel coronavirus, more than half of participants in a recent study who have recovered from COVID-19 are still experiencing “persistent fatigue” related to the disease.

The study, conducted by Dr. Liam Townsend, St. James's Hospital and Trinity Translational Medicine Institute, Trinity College, Dublin, Ireland, and others, found that fatigue was present in more than half of the patients studied “regardless of the seriousness of their infection,” according to a news release on the findings.

As researchers work to understand both the short and long-term effects of the novel coronavirus, more than half of participants in a recent study who have recovered from COVID-19 are still experiencing “persistent fatigue” related to the disease.  (iStock)

“Fatigue is a common symptom in those presenting with symptomatic COVID-19 infection. Whilst the presenting features of SARS-CoV-2 infection have been well-characterized, the medium and long-term consequences of infection remain unexplored," Townsend said in a statement. "In particular, concern has been raised that SARS-CoV-2 has the potential to cause persistent fatigue, even after those infected have recovered from COVID-19."

The study involved 128 patients, all of whom were infected with but had recovered from COVID-19; they were recruited more than two months after their illness.

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The researchers “investigated whether patients recovering from SARS-CoV-2 infection remained fatigued after their physical recovery, and to see whether there was a relationship between severe fatigue and a variety of clinical parameters,” said Townsend. “We also examined [the] persistence of markers of disease beyond [the] clinical resolution of infection."

More specifically, researchers used the Chalder Fatigue Score (CFQ-11), what the release defines as “a commonly used scale to determine fatigue in recovered patients.” In addition, the researchers also took into account the severity of the patient’s initial infection –­­ if they required hospitalization, for instance –­­ as well as any other pre-existing conditions they had that could contribute to the fatigue, such as depression.

“They also looked at various markers of immune activation,” such as white blood cell counts and inflammatory blood markers, for example, but found none, per the release.

Nearly 56% of patients assessed required hospitalization while 44.5% did not. By the end, the researchers determined that more than half of participants — 52.3%, to be exact — reported “persistent fatigue” even after they had recovered from the illness.

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What’s more, even the patients who did not require hospitalization –­­ meaning their illness was less severe –­­ still reported lasting fatigue following infection.

“Fatigue was found to occur independent of admission to hospital, affecting both groups equally," said Townsend.

“There was no association between COVID-19 severity (need for inpatient admission, supplemental oxygen or critical care) and fatigue following COVID-19. Additionally, there was no association between routine laboratory markers of inflammation and cell turnover … and fatigue post-COVID-19,” the release states.

Interestingly, the researchers found that females involved in the study (54%), as well as those with a pre-existing diagnosis of depression or anxiety, “were over-represented in those with fatigue,” according to the findings.

More specifically, two-thirds of the patients who reported persistent fatigue were women.

“And while only 1 person of the 61 (1.6%) without fatigue had a history of anxiety or depression, this proportion was 13.4% (9/67) in those with persistent fatigue,” per the release.

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"I think this study demonstrates that the impact of coronavirus is more than just an infectious disease. It’s also impacting other aspects of our bodies. Other studies are also demonstrating an impact on cardiovascular and neurological systems for some people. I was surprised that fatigue did not correlate with the severity of COVID infection," Dr. John Whyte, the chief medical officer of WebMD, told Fox News in an email.

"It’s something we’re going to have to watch closely and look for predictors as to who may likely experience long-term fatigue. That way, we might be able to more effectively treat it," Whyte, who was not involved in the study, added.

"Our findings demonstrate a significant burden of post-viral fatigue in individuals with previous SARS-CoV-2 infection after the acute phase of COVID-19 illness. This study highlights the importance of assessing those recovering from COVID-19 for symptoms of severe fatigue, irrespective of [the] severity of initial illness, and may identify a group worthy of further study and early intervention,” the study authors concluded, noting their findings “also supports the use of non-pharmacological interventions for fatigue management.”

“These interventions will need to be tailored to the individual needs of the patients, and may include lifestyle modification, cognitive behavioral therapy, and self-pacing exercise, where tolerated,” they said.

The research, which has not yet been published in a peer-reviewed journal, will be presented later this month at a virtual conference held by the European Society of Clinical Microbiology and Infectious Diseases.