Not all patients can heave a sigh of relief once they leave the hospital after receiving treatment for a moderate to severe case of the COVID-19 disease.

More than half of recovering COVID-19 patients surveyed in a new study at the University of Oxford showed tissue abnormalities in their organs two to three months after their initial infection, in addition to compromised mental and physical health.

Researchers looked at 58 patients who had been admitted to Oxford University Hospitals National Health Service Foundation Trust between March 14 and May 25 for COVID-19 treatment. Most of those patients had comorbidities at the time of their hospitalization, which could have played a part in their recovery.

Upon admission, 93% of the 58 patients had an abnormal chest X-ray or CT scan result; at the time of the study two to three months later, 60% had “persistent parenchymal abnormalities” on a lung MRI. Sixty-four percent had significant breathlessness, and 55% complained of fatigue.

As for liver damage, 31% had acute liver injury during admission. Two to three months later, 11% had persistent liver injury on blood tests, while another 10% showed signs of liver injury.

To ascertain if the symptoms were related to COVID-19, the participants were compared to a group of 30 controls who had not been infected by the SARS-CoV-2 virus that causes the disease. The control group had matching gender and age and similar risk factors, such as smoking, diabetes and hypertension.

Damaged Tissues Remain

While COVID-19 is primarily considered a respiratory infection, researchers explored the possibility that it could cause damage to the tissues of several organs. Following a magnetic resonance imaging (MRI) scan, changes in the characteristics of tissues were noticed inside individual organs. “On MRI, tissue signal abnormalities were seen in the lungs (60%), heart (26%), liver (10%) and kidneys (29%) of patients,” the researchers said.

Researchers hypothesized that the strong inflammatory response of the immune system to beat the infection may have contributed to the tissue damage. The extent of tissue change and a person's ability to exercise depended on the level of inflammation, as measured by the presence of antibodies in blood tests, the Oxford study explained.

The fact that none of the controls showed tissue abnormalities in multiple organs, including the brain, added weight to this theory.

“These findings underscore the need to further explore the physiological processes associated with COVID-19 and to develop a holistic, integrated model of clinical care for our patients after they have been discharged from hospital," said study author Betty Raman, MBBS, DPhil, a practicing doctor at Oxford's Radcliffe Department of Medicine, as reported by Reuters.

Mental and Physical Strength Dropped

The infection may also have affect the brain. Brain MRIs of the former COVID-19 patients showed tissue changes, which may have impacted their cognitive reasoning abilities. In addition, regardless of the severity of the case, 35% reported anxiety and 39% reported depression. “COVID-19 survivors experience a high burden of depression, anxiety, as well as reduced quality of life post-hospital discharge,” the paper stated.

To test physical endurance levels, both COVID-19 patients and controls cycled on a stationary bike at a speed that was gradually increased within two minutes. Most participants could not handle this task, indicating that their lungs and hearts were not functioning well. Participants also found it difficult to walk along a corridor for six minutes without stopping.

Similar Research

This is not the first time the spread of the coronavirus to other organs has been studied. Researchers at the Columbia University Irving Medical Center in New York City pointed out that, although COVID-19 starts out as a respiratory infection, it can manifest in other organs, too. According to a study published by Nature Medicine in July, SARS-CoV-2 infection can develop in the renal, gastrointestinal, endocrine, dermatological and neurologic systems.

In another July study based in Rome, nearly 13% of 143 recovered patients, studied 60 days after the onset of the disease, experienced “fatigue (53.1%), dyspnea (43.4%), joint pain, (27.3%) and chest pain (21.7%),” according to a research letter published in JAMA Network. Italian researchers emphasized that further research is required and “continued monitoring after discharge for long-lasting effects is needed.”

Study's Drawbacks

Several limitations to the Oxford study were noted in a preprint version published on Oct. 18 in medRxiv, an archive of research papers awaiting peer approval by other scientists.

One limitation was an absence of peer reviewing by fellow researchers, a process all medical papers undergo to determine the veracity of findings.

Secondly, the small sample size, all from a single medical center, could have prevented the researchers from making accurate estimates. In addition, researchers did not have information on the status of the participants' health before COVID-19.

“The lack of pre-COVID imaging also limits our ability to make causal inferences about the mechanism of multiorgan abnormalities in patients recovering from COVID-19 infection,” the preprint paper said.

Seema Prasad is a freelance health reporter based in Bengaluru, India. She tweets @SeemaPrasad_me