Long Covid

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Post-Acute COVID-19 syndrome (PACS) or Long Covid is a multi-organ disease with a wide spectrum of manifestations. The most prevalent are fatigue (52%), cardiorespiratory symptoms (30-42%), such as dyspnoea, and neurological symptoms (40%), such as headache and attention problems.

Post-Acute COVID-19 includes two subgroups: Long Covid: Persistence of symptoms (present or not at the beginning of the infection) 4 weeks after infection, with a permanent, relapsing or progressive improvement course. Sequelae: Irreversible tissue damage after 12 weeks that could trigger different degrees of permanent dysfunction and associated symptomatology.

The causes of Long Covid are unknown, but some possible ones are believed to be:

Hepatitis A virus

Presence of viral reservoirs: Cells that contain viruses but are inactivated

Sample tube with cryoglobulins

Inflammatory damage in response to acute infection.

Immune system cell with antibodies

Alterations of the immune system produced by the interaction of the virus with the organism.

Legs with varicose veins and a thrombus


Several studies have suggested that 10-15% of patients with COVID-19 may present symptoms weeks or months after infection, although recently they suggest that this figure may even reach 25-30%. In Catalonia, it is estimated that 90,000 patients could be affected by Post-Acute COVID-19.

Children develop asymptomatic or much milder COVID-19 infection than adults. If there are symptoms, they are short-lived. However, mild, asymptomatic cases have been observed with prolonged symptoms, such as insomnia, fatigue, dyspnoea, palpitations, headache, difficulty concentrating and muscle weakness. As age increases, the risk of presenting these symptoms increases.

Although rare, the development of multisystem inflammatory syndrome in children (MIS-C) has been seen. It can appear 3-6 weeks after diagnosis and usually requires treatment to control the symptoms.

There are no studies of persistent symptoms in this group of patients. However, due to inflammation of the placenta, some complications have been described; such as preeclampsia (high blood pressure and signs of damage to some organs); preterm pregnancy (one that occurs between 22 and 36 weeks, 6 days after the last menstruation); an increase in caesarean sections; and, in some patients, alterations in foetal maturation and growth.

The most common symptomatology includes fatigue, which is one of the most predominant and disabling symptoms, along with dyspnoea (a feeling of shortness of breath). These symptoms usually last beyond 4 weeks and can appear intermittently without any damage to explain them.

Situations that can trigger Long Covid:

Long Covid can originate from asymptomatic, symptomatic and severe cases of COVID-19 that required hospitalisation.

Post-Acute COVID-19 cases with sequelae do not always occur in people who have required hospitalisation. The vast majority of patients with pulmonary sequelae are people who have been hospitalised and needed oxygen, ventilation or anti-inflammatory treatment to control the immune response caused by the virus. After this hyperinflammatory phase is over, these patients may have residual pain, lung scarring or even persistent inflammation that may require prolonged treatment.

The coronavirus is a systemic virus that affects the entire body and symptoms are diverse. Post-Acute COVID-19 with involvement of different organs has been observed:

Person holding hands to neck, sweating, pale, unable to breathe, feeling short of breath, choking or breathlessness

Pulmonary effects: dyspnoea (shortness of breath) and coughing.

Monitor with an echocardiogram

Cardiac effects: chest pain, arrhythmias, pericarditis.

Legs with varicose veins and a thrombus

Haematological effects: thrombosis (formation of blood clots) and decrease in blood cells.

Functional neuroimaging

Neurological effects: fatigue, headache, brain fog.

Dizzy woman touches her head


Loss of smell, taste and olfactory hallucinations: This symptomatology does not occur frequently but has been observed with the Omicron variant, and particularly affects young women (under 50 years of age). Patients who do not recover after 6 months, may suffer for a little longer or, in some cases, note sequelae. Therefore, olfactory training must be performed. This consists of teaching the sense of smell again, by exposure to certain fragrances or habitual odours, as there is no current treatment that reverses these symptoms.

Two different sides of the face representing behavioural disturbances or mood swings

Other psychological disorders: these can be due to confinement and social isolation, although it is still unknown if they could also be caused by the viral infection and the immune response triggered to fight the virus. The most common are anxiety, depression, sleep disturbances and post-traumatic stress disorder (PTSD).

Atrophy of the muscles adjacent to the knee

Musculoskeletal effects: muscle pain, joint pain.

Person standing with diarrhoea cramps

Gastrointestinal and hepatobiliary effects: diarrhoea, alteration of intestinal microbiota due to the decrease in beneficial microorganisms.

Glucometer and a hand with a finger in which the lancet has been inserted to measure diabetes levels.

Endocrine effects: diabetes or worsening of some diagnosed cases, irregularities in the menstrual cycle, thyroiditis and bone demineralisation.

Person with dermatitis anywhere on the body

Dermatological effects: hair loss (in 25% of cases), skin lesions and itchy skin.

Diagnosis is fundamentally clinical, based on the presence of symptoms that would not be explained by a cause other than SARS-CoV-2 infection.

Currently, there is no treatment for Post-Acute COVID-19 syndrome, but there is for certain symptoms. After 3 months, many such patients improve and some are discharged.

The key treatment is physical and neurocognitive rehabilitation as well as psychological support. The symptoms of these patients have an impact on their quality of life, both physically and psychologically; therefore, following an approach in these two areas provides substantial improvement.

Physical activity can be difficult for patients with fatigue, and they will not have the same performance as before suffering COVID-19; however, they can improve by following a controlled, scheduled sequential plan.

A prolonged sedentary lifestyle, both in the acute phase and later, can lead to physical deterioration, increased fatigue and intolerance to exertion, as well as musculoskeletal diseases.

More evidence and research conducted by multidisciplinary teams is needed in order to understand the causes of these long-term effects. There is a lack of information on the mechanisms triggered by the infection, to improve the analysis and treatment of such diverse symptoms, and thus to be able to develop preventive and rehabilitation measures.

Globally, this pandemic shows that cases will continue to rise. The Hospital Clínic at Barcelona has prepared a specific consultation programme linked to the Internal Medicine and Pneumology Units attending to these patients; studying how they evolve over time and offering them treatment to alleviate the sequelae they may have.

Substantiated information by:

Antoni Trilla
Eduard Vieta Pascual
Gema Maria Lledó Ibáñez
Jacobo Sellarés Torres
Josep M. Miró Meda
Josep Maria Peri
Maica Rubinat
Mariona Violan

Published: 12 March 2020
Updated: 12 March 2020

The donations that can be done through this webpage are exclusively for the benefit of Hospital Clínic of Barcelona through Fundació Clínic per a la Recerca Biomèdica and not for BBVA Foundation, entity that collaborates with the project of PortalClínic.


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