Novembrer 16-22 2020
What are the stages of COVID-19?
COVID-19 was initially described as a simple respiratory viral infection that presented a threat of comorbidities only in elderly patients. However, COVID-19 is now recognised as a much more complex disease which can affect different organs and can evolve in quite different ways depending on the individual. For this reason, it’s important to describe and characterise the different stages of the illness using clinical and molecular criteria in order to measure its progression and severity. As with cancer, which can be taken as a model for describing an illness’ stages, COVID-19 can be seen as a metastatic pathology, that is to say, where a pathogenic agent spreads from its initial site to other parts of the body.
This study describes COVID-19 through 4 stages, so as to allow doctors to make informed decisions as to the choice of treatments.
What are these stages?
Stage 1: entry of virus into the host where it begins to multiply (asymptomatic)
This stage of asymptomatic infection has been widely described since the beginning of the pandemic. In the overall population it appears that 40% of infected persons have no symptoms, according to the CDC (American Center for Disease Control and Prevention). Infected patients with no symptoms can transmit the virus, but will not require treatment.
Stage 2: Patients show at least one of the following symptoms: fever or chills, coughing, breathing difficulties, tiredness, muscular pains, headaches, loss of taste or smell, sore throat, nausea, vomiting, or diarrhoea. During this stage, where symptoms are apparent and where the virus is actively reproducing in the organism, patients are highly contagious. Diagnostic tests as well as the implementation of protective measures are recommended. During this phase a course of treatment may be put in place (using antivirals and steroids in particular) and it is advisable to be extremely vigilant regarding the possible emergence of other symptoms.
Stage 3: Inflammation in multiple organs (severe symptoms)
Some patients will be affected by this severe stage of the illness, usually 1 to 2 weeks after the onset of symptoms, and will need to be hospitalised. These patients show a worsening of hypoxia (oxygen starvation) and this may lead to damage to certain organs (the heart, kidneys or liver for example). This stage is also characterised by the dysregulation of certain clinical biological markers (IL-6, Calprotectin, Ferritin, soluble CD163).
Stage 4: Endothelial damage, thrombosis and multiple organ failure (critical symptoms).
Only a minority of patients with the virus are so severely affected as to find themselves in phase 4 of the illness. This phase is characterised by severe inflammation and coagulopathy (coagulation disorder) and carries a high risk of death.
Complementary studies need to be carried out in order to evaluate the risks of other chronic symptoms such as cardiac, renal or pulmonary disease in survivors of COVID-19.