A young NHS nurse who died after treating stricken coronavirus patients had fallen ill at work but was not allowed to go home because his ward was so short-staffed, his heartbroken mother claimed last night.

John Alagos, 23, the third nurse and the youngest British medic believed to have succumbed to the deadly Covid-19 virus, collapsed and died at home after an exhausting 12-hour shift.

His mother, Gina Gustilo, 50, told The Mail on Sunday her son had not been wearing the right protective clothing at work.

He returned home on Friday following a night shift, after complaining of suffering a headache and high temperature throughout the night.

John Alagos, a London nurse of 27 who treated covid-19 patients, fell ill at work but was not allowed to go home due to staffing shortages

A tearful Mrs Gustilo said: ‘I asked “Why didn’t you come home?” He said he had asked other staff but they said they were short of staff and they did not let him go. I said, “OK, take some paracetamol.” After a few minutes, I found him turning blue in his bed.’

Mr Alagos was treating coronavirus patients at Watford General Hospital, which last night declared a ‘critical incident’ and shut its A&E department after a problem with its oxygen supplies.

Ms Gustilo said her son’s colleagues told her he was not wearing ‘proper’ protective clothing, adding: ‘They wear PPE, but not totally protective of the mouth. They wear the normal masks.’

After finding her son unconscious in his bedroom, Ms Gustilo immediately called 999 but paramedics were unable to resuscitate him.

Last night, Watford General Hospital said in a statement: ‘Our staff are fully briefed on the symptoms of Covid-19 and we would never expect anyone to remain at work if they were showing these symptoms or indeed were unwell in any way.

‘We have always kept our staff updated on the latest PPE guidance to make sure they have the right level of protection.’ A spokeswoman added: ‘John was very popular and will be missed greatly.’

Mr Alagos, from Watford, was born in the Philippines, but moved to Britain as a youngster and had become a British citizen.

Ms Gustilo said her son did not have any underlying medical conditions.

NHS nurse Aimee O'Rourke, 39, a mother of three died of coronavirus at the Queen Elizabeth the Queen Mother Hospital in Margate, Kent, where she worked

Mother of three Areema Nasreen, 36, who had no underlying conditions, died in intensive care at Walsall Manor Hospital, where she had worked for 16 years

Last week, two other frontline nurses died of Covid-19, believed to have become infected by patients. Mother of three Areema Nasreen, 36, who had no underlying conditions, died in intensive care at Walsall Manor Hospital, where she had worked for 16 years.

And Aimee O’Rourke, 39, also a mother of three, died in intensive care at Queen Elizabeth the Queen Mother Hospital in Margate, Kent, where she worked.

In a heartbreaking Facebook message posted four days before Ms O’Rourke died, her daughter, Megan Murphy, poignantly wrote: ‘We know you are coming home, no maybe about it.

How could my beautiful mum, my forever best friend, the reason I breathe, be so, so poorly after all the good she’s done and does?’

Last night, it also emerged that five London bus drivers had died from the virus.

Leaders of the Unite union called for better protection for drivers and deeper cleaning.

The pandemic also claimed the life of its first prison officer in the UK. Bovil Peter, 64, from Hackney, East London, worked at Pentonville jail in North London where 19 inmates have so far tested positive for coronavirus.

And in a double tragedy, British light-heavyweight boxer Anthony Yarde, 28, announced that he had lost his grandmother to the virus, a week after his father died from the deadly infection.

‘My dad and his mother have passed just days apart,’ the fighter wrote on social media.

‘People are still going out when they don’t need to. I know there’s a lot of opinions about Covid-19 but opinions ain’t worth risking your life and others. Just stay home.’

Meanwhile, renowned Italian footwear designer Sergio Rossi, 84, died in Cesena, a city in Emilia-Romagna, one of the Italian regions hardest hit by the pandemic.