WHY THE AMOUNT OF VIRUS YOU GET IS CRITICAL

WHY do some people bounce back so quickly after the illness, while others spend weeks bed-bound? The answer could lie in the amount of virus an individual is exposed to.

‘People who get a small amount of virus – from a handshake, or something like that – may get sick for a while and then recover,’ Professor Arne Akbar, president of the British Society for Immunology, explains. ‘So in the case of hospital workers, who are continuously exposed to a large amount of virus, it’s likely their recovery period will be longer.’

Many patients will suffer fatigue in the weeks after their illness – this is because the immune system’s extreme response will have depleted energy levels.

As Covid-19 is a respiratory illness, the lungs in particular may take some time before they are back to full health. ‘If you listen to people who’ve had the infection, they may sound as if they are breathing very heavily, even after the virus has left the body,’ says Prof Akbar.

‘The damage has already been done – there may even be scarring in the lungs as a result of the infection.

‘It will take some people a long time to recover from that. It’s not clear yet whether you could in fact be left with these difficulties for the rest of your life.’

But having healthy lungs beforehand is likely to limit the damage – and speed up the recovery time.

Evidence suggests that smokers are less able to fight the infection and will therefore face a longer recovery period.