Acute SARS-CoV-2 infection can cause different clinical manifestations, mainly respiratory, and can also present asymptomatically in a high percentage of cases (in 80% of cases the symptomatology is mild).
In approximately 16.2% of these cases it can become very severe, producing a bilateral hypoxemic pneumonia (with low blood oxygen levels), which makes it necessary to treat patients with high-dose oxygen, including orotracheal intubation in certain cases.
What is persistent Covid or ‘Long COVID’ and how does it manifest itself?
The symptoms of people who are infected with Covid-19 usually disappear within 4 weeks and, exceptionally, may last up to 12 weeks after infection. Persistent Covid or Long COVID is a syndrome characterized by the persistence of COVID-19 symptoms weeks or months after the initial infection, or by the appearance of symptoms after a period of time without them.
It is an emerging pathology of which, at present, many studies are being carried out, in which it is deduced that about 15-25% of patients who have suffered Covid-19 may present persistent Covid.
Furthermore, according to an international survey and another Spanish survey, only 30-48% of patients with persistent Covid have a positive diagnostic PCR performed. Although it is true that almost all patients with this pathology have had access to this diagnostic test. The WHO has recognized it as a disease, although it assumes the category of “probable”, when there is no confirmation of infection in the absence of PCR or antibodies (prior to the administration of the vaccine).
It is essential to differentiate this pathological entity from the so-called “Covid sequelae or post-Covid pathology”, in which there is a history of severe Covid involvement in its acute phase, which has frequently required hospital admission, even in critical care units (ICU) and which present symptoms derived from the sequelae following the structural damage of the complications suffered (mainly of a respiratory nature such as fibrosis or pulmonary hypertension).
Clinical manifestations of persistent Covid
A large number of symptoms have been described, which may be persistent or fluctuate over time. In addition, they may worsen with physical and mental exertion. Data based on several surveys, with more than 3,000 patients from 56 different countries and another one carried out in Spain with more than 1,800 affected patients, suggest that cases of persistent COVID could register up to 205 different symptoms.
The most frequent symptoms, according to these surveys are: asthenia, general malaise, muscle or joint pain, sleep disturbances, persistent fever or low-grade fever, headache, “mental fog”, difficulty concentrating, loss of taste and smell, paresthesias and mood disturbances, memory lapses, cough, shortness of breath, diarrhea, loss of appetite, stomach pain, rash, hair loss, weak nails, difficulty swallowing, ringing in the ears, dry eyes or conjunctivitis, palpitations and fluctuations in blood pressure.
Therefore, as we can see, the symptomatology varies from general, neurological, psychic/emotional symptoms to locomotor, respiratory, digestive and cardiovascular alterations.
What is the cause of this syndrome?
There are several hypotheses in this regard. These are:
- The persistence of the virus in the organism, after the acute phase of the disease, originating a latent or chronic infection.
- The infection triggers an inflammatory storm called “cytokine storm”, generating a late inflammatory immune response, which would mainly affect cellular immunity (that mediated by T lymphocytes).
- Existence of autoantibodies in COVID-19, which can act against immunomodulatory proteins, altering immune function.
What side effects are associated with it?
This condition has important consequences in the workplace, due to the need for patients to take time off work in various situations, with the added difficulty that this pathology is not currently classified as a common disease, nor is it included in the scales used to determine the causes of incapacity for work. Likewise, the impact on the patient’s quality of life is an essential factor to take into account, since it can significantly limit the daily activity of any person suffering from these symptoms.
What are the long-term health consequences of persistent Covid?
We do not know at the present time whether these symptoms can persist indefinitely, but we do have patients under follow-up who were infected with Covid in the “first wave” (March 2020) and are currently showing symptoms of persistent Covid. In other cases the symptoms have attenuated and there are a few cases in which the symptomatology has disappeared after several months. The cause of this different evolution of the disease is not known.
Does it affect all age groups equally, and which group is currently the most affected?
According to the survey conducted by the Spanish Society of General and Family Physicians (SEMG) and the LONG COVID ACTS affected groups, persistent COVID is more frequent in women (79%) in middle age. However, it can occur at any age and with symptoms persisting for more than 6 months.
Its onset is not related to the severity of the initial infection, so it can affect both patients who have had a mild form of the disease and severe patients who have been hospitalized in a conventional ward and/or ICU.
Is there any treatment?
At present, treatment is symptomatic, although it is advisable to go to units specialized in post-COVID pathology or to expert consultations such as an Internal Medicine specialist with experience in this type of cases.
Preventive aspects based on vaccination of the adult population in general and hygiene measures (masks, frequent hand washing and safety distance) are essential to avoid the spread of Covid-19 and, therefore, prevent the development of persistent Covid.