YOUNG coronavirus patients suffer a hidden drop in oxygen levels, a top doctor is warning.
Professor Babak Javid, consultant in infectious diseases at Cambridge University Hospital, revealed youngsters with Covid-19 may appear to have mild symptoms but actually need urgent hospital treatment.
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And he warned that coronavirus patients may suffer these life-threatening drops in their blood oxygen levels and barely notice.
Prof Javid told BBC Radio 4's Today programme: "Although the virus causing Covid can affect many organ systems, it's primarily an infection of the lung so it's not surprising that there are problems with the oxygenation of the blood by the lungs.
"But sometimes, especially in younger people, the symptoms of this can be fairly mild or non-specific such as being very tired when you try to do your daily activities.
"Unless you're to actually measure the oxygenation of the blood and then it's actually surprisingly low."
Prof Javid described that it is relatively easy to measure blood oxygen levels through using a simple device called pulse oximeter.
'Real warning signal'
Pulse oximeters clip over the fingertip or ear to measure blood oxygen levels in the body and tell you how well the heart and lungs are working.
They work by emitting a beat of light through the finger to a sensor on the other side of the unit.
Oxygenated and non-oxygenated blood absorbs light differently, so the device looks at the pattern of light to determine the amount of oxygen in the blood.
That reading is then displayed on its digital screen.
Prof Javid added: "One of the danger signs is actually if it dips below what would be a normal reading – a normal reading is about 96 per cent – especially on even mild exercise like walking up the stairs of going for just a short walk.
"If it dips at that time that's the real warning signal."