Nine months into the pandemic, it has become clear that patients’ health problems may not end when their acute COVID-19 infection does. 

While formal research into the virus’s long-term implications is still too nascent to provide clear insights, anecdotal evidence of post-recovery health problems has begun to mount. In mid-November, the Centers for Disease Control and Prevention (CDC) updated its summary of reported long-term symptoms to include feelings of fatigue, shortness of breath, achy joints, brain fog, and damage to the heart, lungs, and brain that persists for weeks or months. 

“At the beginning, everything was acute, and now we’re recognizing that there may be more problems,” Helen Su, an immunologist at the National Institute of Allergy and Infectious Diseases, recently told reporters for Nature. “There is a definite need for long-term studies.”

These emerging post-infection symptoms are notable both for their variety and pervasiveness across age demographics. In July, the CDC shared the results of a survey that assessed patient recovery two to three weeks after the subjects received their positive test results. Researchers found that well over a third (35 percent) of all participants had not returned to their normal state of health at the time of inquiry, with many still experiencing symptoms such as a persistent cough, fatigue, or shortness of breath. This pattern persisted across age lines, affecting 26 percent of patients aged 18-34 years, 32 percent of those between 35 to 49, and 47 percent of those over 50. 

“These findings indicate that COVID-19 can result in prolonged illness even among persons with milder outpatient illness, including young adults,” CDC researchers concluded. 

To make matters more concerning, these lingering effects have been reported even among patients who would appear to have the least risk of developing long-term complications. As a notable example — earlier this year, Eduardo Rodriguez, a professional athlete who had been projected to be the Red Sox’s #1 starter before his COVID-19 diagnosis, suffered from fatigue symptoms well after his recovery and, upon his return to the pitch weeks later, struggled to get through his warm-up throws. The experience, he told reporters, left him feeling “100 years old.”

The evidence we have now is limited and primarily anecdotal. The novel coronavirus is, as its name suggests, novel — and for that reason, we do not yet have a wealth of literature on the impact that COVID-19 infections might have on long-term patient health. However, we do have some preliminary research on how the virus may contribute to the development of chronic conditions. So far, these findings appears to fall into three major categories: heart concerns, chronic fatigue, and cognitive impairment. 

COVID-19 As a Cause of Cardiovascular Disease

In July, researchers from the University of Salamanca published a preprint of a cross-sectional descriptive study that examined the post-COVID prevalence of pericarditis and myocarditis in healthcare workers. Their investigation found that the two conditions can occur with clinical stability post-infection, even in asymptomatic subjects. As they write, “These observations will probably apply to the general population infected and may indicate that cardiac sequelae might occur late in association with an altered (delayed) innate and adaptative immune response.”

An earlier study of patients in Wuhan similarly reported acute myocarditis and myocardial damage occurring during COVID-19 infections. Among 68 deaths in a case series of 150 patients confirmed to have the virus, seven percent occurred as a direct result of myocarditis. In 33 percent of cases, researchers believed that myocarditis played a contributing role in the patient’s demise. 

How the virus relates to myocarditis is currently unclear. Research to date suggests that the latter may result from the virus attacking the heart. However, myocarditis could also occur when the body’s overly-aggressive immune response triggers inflammation.

While we don’t yet know how long these cardiovascular symptoms might last, there is a chance that they could extend for years. Past investigations of pneumonia patients indicate that recovered patients may be at an increased risk of cardiovascular disease for up to a decade. However, given that there is little information on how SARS coronaviruses influence long-term heart health — and none on COVID-19 specifically — we will need more research to know for sure. 

COVID-19 As a Cause of Chronic Fatigue

Multiple reports have established that chronic fatigue is one of the most common symptoms experienced by those who feel unwell two weeks after COVID-19 onset, often persisting weeks or months after their acute condition subsides. 

As one writer for Medscape recently summarized these research findings

“Although some of the reported persistent symptoms appear specific to SARS-CoV-2 — such as cough, chest pain, and dyspnea — others overlap with the diagnostic criteria for [myalgic encephalomyelitis/chronic fatigue syndrome], which is defined by substantial, profound fatigue for at least six months, post-exertional malaise, unrefreshing sleep, and one or both of orthostatic intolerance and/or cognitive impairment. Although the etiology of ME/CFS is unclear, the condition commonly arises following a viral illness.”

It is worth noting that we have seen occurrences of chronic fatigue with another coronavirus, SARS CoV-1. Past research indicates that chronic post-SARS patients experience persistent fatigue, weakness, depression, nonrestorative sleep, and diffuse myalgia. One case-controlled study found that its participants — healthcare workers who had contracted the disease in 2003 and experienced chronic fatigue, musculoskeletal pain, and disturbed sleep patterns — continued to suffer the effects for between one and three years following their infection. None, the researchers found, were able to return to work within a year. 

It is unclear whether similar chronic fatigue symptoms will impact post-infection COVID-19 patients as severely or for as long. However, given the apparent commonality of persistent post-recovery fatigue among recovered cases, the possibility seems to be one worth investigating further. 

COVID-19 As a Cause of Dementia-Like Symptoms

Over the last few months, prolonged cognitive impairment has emerged as a troubling long-term side effect of COVID-19. Some recovered patients have reported experiencing persistent brain fog symptoms and say that they struggle to focus amid bouts of dizziness, memory loss, and confusion. This is alarmingly common among severe cases; one recent French study on 120 patients who had been hospitalized due to COVID-19 found that over a third (34 percent) of those surveyed had memory loss, and 27 percent struggled to concentrate even months after their recovery. 

In some cases, these effects are so severe that patients find it challenging to work and care for themselves. In mid-October, the New York Times interviewed several such patients, including one former lawyer who ultimately needed to take a leave of absence from work and return a foster dog she had recently taken in because she felt ill-equipped to handle the responsibility. 

“I’m scared,” she wrote in a message to her boss. “I really want to get back to work. But, I keep getting really tired and really confused.” 

For now, doctors are unsure of what causes brain fog, how long it might last, or why it appears after mild and severe COVID cases alike. Some theorize that it occurs when the body’s immune response leads to inflammation in the blood vessels leading to the brain; however, the veracity of this will need to be confirmed through further investigation. 

Over the last several months, it has become abundantly clear that COVID-19 will leave some patients with health considerations that persist long after their initial infection has passed. We need to gain a better understanding of what these conditions are, how long they last, and what kind of care affected patients will need in the long-term. To that end, continued research efforts will be critical to supporting patients during and in the aftermath of the pandemic.