Mild or moderate cases have been generally defined based on less severe clinical symptoms (low grade fever, cough, discomfort) with no evidence of pneumonia. 6,10 More Severe Illness Pneumonia and Hypoxemia indicate more severe illness (O2 Sats <95%. In someone with pre-existing COPD, may be lower - depends on usual sats when well) Diagnosing pneumonia T > 38 RR > 20 breaths/ minute HR > 100 New confusion Plus clinical impression: The diagnostic accuracy of  “overall clinical impression” is close to ruling in pneumonia, in an emergency. (Systematic Review of 9 studies 2019) Other distinguishing symptoms and signs that help identify patients with more severe illness to make the decision about hospital admission, see When to Refer to ED and Who to Call for Acute Care Advice in the next tab on this page. Distinguishing from bacterial pneumonia It is difficult to distinguish between viral and bacterial pneumonia. However, as community prevalence becomes higher patients will be more likely to have a COVID viral pneumonia than a bacterial pneumonia. The UK National Institute for Clinical Excellence suggests these things may help: COVID pneumonia more likely Patient has had typical COVID symptoms for about a week Has severe muscle pain (myalgia) including chest wall myalgia Has recent onset loss of sense of smell / taste Feels breathless but has no pleuritic pain Has a history of potential COVID exposure (this may become less important as community prevalence increases) Note also Return of cough after period of improvement may signal development of COVID pneumonia Return of fever after afebrile period may signal development of COVID pneumonia Bacterial pneumonia more likely Becomes rapidly unwell after a few days of symptoms No history of typical COVID symptoms Pleuritic pain Purulent sputum