People who do not follow social distancing rules or wear masks "have blood on their hands", an intensive care doctor has warned.
Prof Hugh Montgomery told BBC Radio 5 Live hospitals were facing a "tsunami" of Covid cases and he feared it would get worse after New Year's Eve.
He urged people to accept that it was going to be a "miserable" occasion this year and not to gather in groups.
It echoes official advice to stay at home and not hold parties.
About 44 million people in England are now living under the toughest level of Covid restrictions after tier four was expanded at midnight.
A further 50,023 new Covid cases were recorded in the UK on Wednesday, as well as 981 more deaths within 28 days of a positive test - more than double the previous day's total.
Prof Montgomery, who works in intensive care at London's Whittington Hospital, and leads a research group at UCL, said: "We are in a lot of trouble in UK intensive care now.
"Just huge numbers coming in, my heart goes out as well to our emergency departments, seeing a tsunami in the last week or two of cases. Everyone is working at maximum stretch."
He told Radio 5's Rachel Burden it was wrong to blame the surge in cases and deaths on the new variant of coronavirus, which was only "slightly" more transmissible and caused the same symptoms.
"It is making me actually very angry now that people are laying the blame on the virus, and it is not the virus, it is people, people are not washing their hands, they are not wearing their masks," he said.
'People will die'
And he warned anyone not social distancing or following the rules that they "have blood on their hands".
"They are spreading this virus. Other people will spread it and people will die. They won't know they have killed people but they have."
He added: "I am watching whole families getting wiped out here, and it's got to stop."
Prof Montgomery, who was on shift as he gave the interview to 5 Live, said it was "a great myth" that hospitals are being overwhelmed with elderly people.
"The people we are getting are, like the first wave, my age really. I am 58 and I would say half the patients are younger than me. It is middle-aged people or a little bit older that we are getting."
He also told how he had gone home for a shower after one of his shifts and been called back because a pregnant patient had deteriorated.
And he issued a plea to people thinking of seeing in the New Year later with a party: "I am really sorry this New Year is going to be miserable, but it has to be. Please don't gather in masses. Don't make this a last swansong."
Prof Montgomery's warnings echo advice from NHS England's Prof Stephen Powis, who told a Downing Street press conference on Wednesday: "Covid loves a crowd, so please leave the parties for later in the year."
And in Scotland, First Minister Nicola Sturgeon has already warned people not to celebrate Hogmanay in the traditional way amid a lockdown across the mainland.