Clinical and immune-related manifestations in patients with COVID-19

In late 2019 a previously unknown infection affected many people in China. The disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was identified as coronavirus disease 2019 (COVID-19). In a very short period of time, the virus spread worldwide, so on March 11, 2020, the World Health Organization (WHO) declared a pandemic. Various studies have focused on the risk factors and pathogenesis of the virus and have distinguished different phases of the disease (viremic, hyperinflammatory phase and phase of complications) characterized by a wide range of clinical manifestations. Most patients experience mild flu-like symptoms, but severe disease and even death are possible. The main clinical manifestations are of the respiratory system with lung involvement. Damage caused by COVID-19 is observed in various organs and systems (nervous, endocrine, cardiovascular, excretory system, gastrointestinal tract, liver, immune system, eyes, etc.). In some patients, some of the symptoms may persist for weeks or months after the onset of infection (so-called "long COVID", "post-acute COVID-19" and "post-COVID syndrome (PCS)"). Antiphospholipid syndrome, systemic vasculitis, myositis, arthritis, systemic lupus, skin manifestations, hematological involvement, neurological involvement (Guillain-Barre syndrome, transverse myelitis, etc.), optic neuritis, cardiovascular involvement, acute pancreatitis, glomerulonephritis, thyroiditis, anterior uveitis, conjunctivitis, etc. stand out among them. Unfortunately, children are hit hard by COVID-19. In them, the viral load of SARS-CoV-2 is greater than in adults. More than 700 cases of a unique multisystem inflammatory syndrome in children (MIS-C) characterized by clinical and laboratory manifestations similar to Kawasaki disease and toxic shock syndrome have been described. The disease is severe - about 73% require intensive care, and the overall mortality is about 1.7%. Clinical criteria, laboratory parameters, analysis of blood oxygen saturation, imaging studies and RT-PCR (diagnostic gold standard) are used for the diagnosis of COVID-19. In patients with COVID-19, an individualized therapeutic approach is required. Since the beginning of the pandemic, affected countries have tried to flatten the epidemiological curve and avoid overloading health care systems by imposing specific hygiene measures, limiting social contact, wearing a mask, physical distance, travel restrictions, border closures, national lockdowns and mandatory quarantine for the infected and their contacts. In a short period of time, many highly effective vaccines have been developed, most with mild side effects after administration. Unfortunately, more severe reactions are possible after vaccination, but nevertheless the benefit outweighs the risk. This review aims to present the main clinical manifestations in patients with COVID-19 and the possible complications or post-covid syndromes.