Patients with COVID-19 who are admitted to hospital should have their oxygen saturations monitored regularly, because patients can look clinically very stable even when their oxygen saturations are falling.

In COVID-19, the oxygen saturations are an important part of monitoring the disease trajectory; deterioration can happen over a few hours, so it’s important to recognise that even a slight increase in oxygen demand by the patient can be an important sign that their disease is worsening.