John Alagos, 23, is the youngest nurse known to have succumbed to coronavirus.
He collapsed and died at home after an exhausting 12-hour shift treating Covid-19 patients at Watford General Hospital.
His mother, Gina Gustilo, 50, claimed he had fallen ill at work but was not allowed to go home because his ward was so short-staffed.
She also said her son had not been wearing the right protective clothing at work.
Alagos returned home from a night shift on April 3, saying he had been suffering with a headache and high temperature throughout the night.
Mrs Gustilo told the Mail on Sunday: “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.”
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.”