A clinical-therapeutic staging proposal for COVID-19

Simon Collins, HIV i-Base

This short paper proposes a three-stage classification for COVID-19, with increasing severity that corresponds with distinct clinical findings, responses to therapy and clinical outcomes.

Stage I (mild) – early infection

The initial stage occurs at the time of inoculation and early establishment of disease. For most people, this involves an incubation period associated with mild and often non-specific symptoms such as malaise, fever and a dry cough.

Stage II (moderate) – pulmonary involvement (IIa) without and (IIb) with hypoxia:

In the second stage of established pulmonary disease, viral multiplication and localised inflammation in the lung is the norm. During this stage, patients develop a viral pneumonia, with cough, fever and possibly hypoxia (defined as a PaO2/FiO2 of <300 mmHg).

Stage III (severe) – systemic hyperinflammation:

A minority of COVID-19 patients will transition into the third and most severe stage of illness, which manifests as an extra-pulmonary systemic hyperinflammation syndrome. In this stage, markers of systemic inflammation appear to be elevated. COVID-19 infection results in a decrease in helper, suppressor and regulatory T cell counts.


Siddiqi HK et al. A clinical-therapeutic staging proposal COVID-19 illness in native and immunosuppressed states: a clinical-therapeutic staging proposal. Journal of Heart and Lung Transplant. DOI: 10.1016/j.healun.2020.03.012

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