Study: Initial COVID-19 Severity May Not Predict Later Complications

A new study has found that the severity of an initial COVID-19 infection does not necessarily predict what later complications or long-lasting symptoms a person may experience.

The results, published in The Annals of the American Thoracic Society this month, set out to examine the overall wellness and recovery of lung function in 153 participants who had experienced varying degrees of COVID-19 symptoms and severity.

"We found that fatigue, ill-health and breathlessness were all common following COVID-19," Liam Townsend, MD, one of the co-authors of the study, said in a news release. “However, these symptoms appeared to be unrelated to the severity of initial infection or any single measurement at the time of an outpatient appointment."

The study’s participants were followed for approximately 75 days following their COVID-19 diagnosis. The researchers graded the initial severity of the infection using the following factors:

1. An infection that did not require hospital admission
2. Those patients who had an infection that required hospital admission
3. Infections that required intensive care

Of the 153 study participants, nearly half required hospital admission during their infection. Researchers reported that at the conclusion of the study, 62% of the participants had not fully recovered, while another 47% reported having ongoing fatigue. The researchers also assessed the participants' health based on the correlation between their symptoms and level of exertion during a six-minute walk test.

The researchers found that the level of severity of the virus in patients, in the beginning, was not necessarily correlated with persistent or worsening respiratory symptoms later in the course of the illness.

"These findings have implications for clinical care, in that they demonstrate the importance of following up all patients who were diagnosed with COVID-19, irrespective of severity of initial infection," Townshend said in the press release. "It is not possible to predict who will have ongoing symptoms."

What Does This Mean for COVID-19 Diagnoses?

The study points at a larger question surrounding a COVID-19 diagnosis: What does it mean for a person’s health in the aftermath? 

“It is clear that the severity of COVID-19, mild or severe, does not predict whether you will suffer long-term COVID-19 symptoms,” William W. Li, MD, president and founder of The Angiogenesis Foundation and author of Eat to Beat Disease, tells Verywell. “If you’ve recovered and feel unusual, even months later, it is important to let your doctor know in case you are suffering from ‘long-hauler’s syndrome’ which can affect anywhere from 10% to 80% of people after recovering from the initial COVID-19 infection.”

What’s important to keep in mind, Li says, is that COVID-19—no matter if it initially leads to minor symptoms or treatment in the ICU—can cause health issues long after the initial recovery.

“Some of the symptoms of long-term COVID-19 syndrome include brain fog, racing heart, extreme muscle weakness, shortness of breath, and more than 100 other manifestations,” he says.

Continued Research Needed

Beyond the fact that this research points at the potential for a COVID-19 diagnosis to affect a person's health over time, it also points at a necessity to develop biomarkers that can help healthcare professionals determine which patients who have COVID-19 will develop these long-term health issues before they become an issue, Li says.

"The basic measures of illness are not able to do this, so researchers are now looking in the blood for signals at the cellular, molecular, and even genetic level," he says. "Long-term COVID-19 seems to be a combination of vascular damage from the virus combined with the body’s immune system overreacting and causing autoimmune damage and chronic inflammation, as well as nerve damage."

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