Various studies have confirmed that COVID-19 is a multi-organ disease with a broad spectrum of manifestations, which last for 14-110 days after infection. An article published in Nature Medicine observed that 80% of patients infected with SARS-CoV-2 developed one or more long-term symptoms, with the most common including fatigue (58%), headache (44%), difficulties concentrating (27%), hair loss (25%), dyspnoea (24%), and anxiety and depression (13%).
The most common consequences at the pulmonary level are a feeling of suffocation and decreased oxygen in the blood, which makes physical exercise and other activities difficult. Some cases of thrombosis have also been observed. These are currently treated with oral anticoagulants and heparin. From a cardiovascular point of view, the long-term sequelae include myocardial fibrosis, arrhythmias and tachycardia.
Furthermore, the SARS-CoV-2 virus has broad effects, including on the brain. The most common neuropsychiatric effects are fatigue, muscular pain, headache, and brain fog. There are also cases of autonomic dysfunction. This is the disruption of the autonomic nervous system, which controls the internal organs’ automatic functions. Depending on the nerves affected, it can cause dizziness, difficulty digesting food, urinary incontinence, erectile dysfunction, and other symptoms.
Cases involving anxiety, depression, sleep disturbances, and post-traumatic stress disorder (PTSD) make it difficult to lead a normal life, and are also quite common. It is not yet known whether these are a result of lockdown and social isolation, or of the viral infection itself and the immune response triggered to fight it, which could potentially affect certain areas of the brain and cause these symptoms.
Because it is a systemic virus, there are episodes of acute kidney damage because the kidney’s filtration rate is reduced for up to 6 months following infection. At the endocrine level, new cases of diabetes or worsening of some previously diagnosed cases have been observed. From a digestive point of view, the virus also alters the gut microbiota, causing a decrease in beneficial micro-organisms. The dermatological effects are basically hair loss in 25% of people infected with COVID-19.
These effects can occur regardless of the severity of the initial infection, and are much more common in women than in men, and also in middle-aged people (30-50 years). It is thought that the higher incidence in women is because they may have a more reactive immune system. Symptoms may appear following recovery, or may persist from the onset of the disease, and may fluctuate or cause relapses over time.
Factors that may contribute to the development of long COVID include cellular damage caused by the virus following infection, having a robust immune system with inflammatory cytokines (immune system molecules that promote inflammation), and having a procoagulant state induced by SARS-CoV-2.
But for now, these are just hypotheses. More evidence and research conducted by multidisciplinary teams is needed in order to understand the causes of these long-term effects. The information on the mechanisms triggered that is needed in order to improve analysis and treatment of such diverse symptomatology, and thus to develop preventive and rehabilitative measures, is lacking. This pandemic has shown that these cases will continue to increase globally. Hospital Clínic de Barcelona has created a specific clinic to attend to all these patients, study how they develop over time and offer them treatment to alleviate the symptoms they present.
