200 participants should be included in the study. There will be three groups: 100 participants with a severe course of the disease 3 months ago, 50 asymptomatic carriers of coronavirus infection 3 months ago and 50 people who were in close contact with patients with confirmed coronavirus infection 3 months ago, but not sick and without antibodies to SARS-CoV-2.

The study consists of two visits. At the first visit, after signing the consent to participate in the study, a screening examination will be performed to assess the criteria for inclusion and exclusion in the study.

At the second visit, patients who meet the inclusion criteria and do not have exclusion criteria will undergo clinical and instrumental examination, and biological samples will be collected for laboratory testing.

The aim of the study is to determine the most significant clinical and laboratory markers of the severity of the outcomes in the period of convalescence of the new coronavirus infection COVID-19. Clinical and laboratory indicators, the number and severity of signs of postcovid syndrome as well as pathological changes in lung tissue according to CT data in the group with covid pneumonia and indicators of immune status, hemostasis, endothelial dysfunction, inflammation, metabolism will be assessed.

Inclusion Criteria:

For all groups:

• Informed consent signed by the patient.
• Men and women aged 18 and over.

Group COVID-19 (asymptomatic):

• Confirmed diagnosis of COVID-19 (positive SARS-CoV-2 RNA PCR test or history of IgM and / or IgG antibodies to SARS-CoV-2)
• Absence of any clinical symptoms associated with coronavirus infection.

Group Healthy:

• Contact with patients with symptomatic new coronavirus infection COVID-19 in the absence of personal protective equipment for at least 3 days.
• Absence of any clinical symptoms associated with coronavirus infection

Group COVID symptomatic:

• Confirmed diagnosis of previous COVID-19 (positive SARS-CoV-2 RNA PCR test or presence of IgM antibodies to SARS-CoV-2) in history.

• A severe course of COVID-19, characterized by one or more of the following symptoms:

  • Respiratory rate ≥ 30 in 1 min
  • Blood oxygen saturation (SpO2) ≤ 93%
  • The ratio of the partial tension of oxygen in arterial blood to the fraction of oxygen during inspiration (PaO2 / FiO2) <300
  • Lung tissue lesion> 50% and / or according to computed tomography CT-2 and higher
  • Septic shock / sepsis
  • Development of multiple organ failure
  • Cytokine storm

Exclusion Criteria:

• Pregnancy
• Covid-19 vaccination
• Any serious medical illness before coronavirus infection, as well as a permanent form of atrial fibrillation
• Regular intake of anti-inflammatory, antibacterial, cytostatic and immunosuppressive drugs
• Refusal to participate in the study

Men and women aged 18 and over with asymptomatic or severe course of the novel coronavirus infection COVID-19, or who have been in close contact with patients with confirmed coronavirus infection, but who are not sick and do not have antibodies to SARS-CoV-2