There are half a million cases of coronavirus around the world, the World Health Organisation (WHO) has said.

And 20,000 deaths have been linked to Covid-19, the global health body said.

WHO reiterated its warning that young people are “not invincible”, adding that the infection can cause severe disease in “people of all ages”.

The evidence to date suggests that most children who develop Covid-19 have mild symptoms.

But WHO said it had reports which describe severe disease in children, including two deaths.

And one in 10 people aged 20 to 50 will have “moderate to severe” illness.

Meanwhile a vaccine is still “at least 18 months away” WHO said, but it urged caution against using drugs not proven effective.

WHO’s director general Dr Tedros Adhanom Ghebreyesus said: “There are now more than half a million confirmed cases of Covid-19 and more than 20,000 deaths.

“These are tragic numbers, but let’s also remember that around the world there are hundreds of thousands of survivors.”

Dr Ghebreyesus said the global shortage of personal protective equipment “is now one of the most urgent threats to our collective ability to save lives”.

How coronavirus symptoms compare
(PA Graphics)

“When health workers are at risk, we’re all at risk,” he added.

Dr Ghebreyesus continued: “A vaccine is still at least 18 months away.

“In the meantime, we recognise that there is an urgent need for therapeutics to treat patients and save lives.

“Today we are delighted to announce that today in Norway and Spain, the first patients will shortly be enrolled in the Solidarity Trial, which will compare the safety and effectiveness of four different drugs or drug combinations against Covid-19.

“In the meantime, we call on individuals and countries to refrain from using therapeutics that have not been demonstrated to be effective in the treatment of Covid-19.

“The history of medicine is strewn with examples of drugs that worked on paper, or in a test tube, but didn’t work in humans or were actually harmful. We must follow the evidence. There are no shortcuts.”

When asked about the impact of the virus on different age groups, Dr Maria Van Kerkhove, WHO’s Covid-19 technical lead, said: “This virus is capable of causing infection and severe disease in people of all ages.

“What we know from data is that this virus can cause mild disease, moderate disease – classed as people with pneumonia but don’t need oxygen support. It can cause severe disease, critical disease and it can kill some people.

“Among children, the majority of children that are infected are experiencing mild disease but we do have reports that describe severe disease in children. We have reports of deaths in children – one in China and one in the United States.”

Dr Mike Ryan, executive director of the WHO’s emergencies programme, added: “We will find in Germany and other countries up to 10 to 15% of people under 50 with disease will have a moderate to severe infection.

“For most young people this is a mild infection but for a significant minority of people between the age of 20 and 60 this is a significant infection. If you listen to people interviewed on the media the one thing I’ve seen again and again is adults and young adults who got this keep saying ‘this is not flu’.”