Clinical and Biological Characterization of Post COVID-19 Syndrome

The goal of this observational study is to describe the symptoms that persist for more than 12 weeks after the acute episode in participants who had COVID-19, and compare the functional, socioeconomic and occupational effects with a post-COVID-19 control group without persistent symptoms after the COVID-19 acute event.

The main questions it aims to answer are:

* What are the characteristics of symptoms that persist for more than 12 weeks in participants who have had COVID19 in the last year?
* What are the health-related quality of life and psychosocial effects in participants with persistent symptoms of COVID-19, compared to a post-COVID-19 control group without persistent symptoms after the acute episode of COVID-19?

Two groups of cases and one group of controls will be included. A group of cases with persistent respiratory and/or cardiovascular symptoms (cardiorespiratory cases), and another group with persistent non-cardiorespiratory symptoms.

Participants who report at least two symptoms of intensity greater than or equal to severe will be classified as non-cardiorespiratory cases.

Controls will be participants with a history of confirmed SARS-CoV-2 infection, but without current or past persistent symptoms (ie, who resolved their symptoms during the acute episode or whose symptoms did not persist more than 4 weeks after onset).

Controls will be matched to cases by sex, age (with a margin of up to ±5 years), and time since diagnosis of the COVID-19 episode considered as the origin of post-COVID-19 symptoms in the cases (with a margin of of ±30 days).

The visit will include the application of the questionnaires for the evaluation of symptoms and quality of life associated with health, the clinical evaluation and the extraction of a blood sample.

The extraction of a blood sample will allow biochemical determinations, the complete blood count and vitamin D level to be carried out. Subsequently, an aliquot will be reserved for mechanistic evaluation (inflammatory markers, immunological and microRNA studies).

Eligibility Criteria:
Two groups of cases and one group of controls will be included. A group of cases with persistent respiratory and/or cardiovascular symptoms (cardiorespiratory cases), and another group with persistent non-cardiorespiratory symptoms. For participation in the study, people who meet the following inclusion criteria and none of the exclusion criteria will be considered.

Inclusion Criteria:

* Age equal to or greater than 18 years;
* Documented SARS-CoV-2 infection by PCR or antigen test;
* Ability to understand the objectives of the study;
* Acceptance to participate in the study and willingness to sign the informed consent.
* Permanent residence in Buenos Aires Metropolitan Area.

Exclusion Criteria:

* Women who report being pregnant, who are in the puerperium or lactation period at the time of the evaluation.
* People with known chronic debilitating conditions, defined as:

  i. heart failure, ii. symptomatic Coronary Heart Disease, iii. Diagnosis of cancer in the last 5 years iv. symptomatic anemia, v. chronic obstructive pulmonary disease or greater than moderate asthma, vi. heart valve disease more than mild, vii. cognitive impairment prior to the diagnosis of COVID-19, viii. diagnosis of schizophrenia or depression, ix. any other condition that, at the discretion of the treating professional or the research team, may explain or justify the aforementioned symptoms.
* Participants who are undergoing an acute pathology or who have undergone it in the last 4 weeks. In this case, they may be contacted again, after the period of time considered acceptable by the treating professional or the research team to invite them to participate.