Department for Health confirms the child, who had an underlying health condition, is the youngest in the UK to die with COVID-19.
Another 708 people have died after testing positive for coronavirus – including the youngest ever UK victim aged five – taking the UK’s total to 4,313.
The daily increase in deaths, which includes cases from up to 5pm on Friday, comes after the figure rose by 684 on Friday and 569 on Thursday.
Public Health England said of the extra 637 English deaths in hospitals, patients were aged between five years and 104 years old.
Before today, the youngest known victim was 13. The Department for Health has since confirmed the five-year-old is the UK’s youngest person to die with COVID-19 related symptoms so far.
It brought the total number of confirmed reported deaths in hospitals in England to 3,939, with 40 of those who had died in England – aged between 48 and 93 years old – having no known underlying health conditions.
No information was released about the five-year-old, but the implication is that the child had an underlying condition.
The largest share of deaths occurred in the Midlands, with 212 deaths in the region, 127 in London and less than 100 in other regions. The least hit region was the South West.
Previously, the largest share of deaths was in London, which has also experienced the highest rates of infection.
Cabinet member Michael Gove referred to sharply rising rates occurring in Yorkshire and in the Midlands, with rates falling slightly in London, during the government’s daily briefing from Downing Street.
Meanwhile, the number testing positive for COVID-19 in the UK as a whole has risen to 41,903, as of 9am on Saturday, after 183,190 have been tested.
The number of people in Scotland who have died is 218, up 46 from 172 on Friday, the Scottish Government said.
Public Health Wales said 13 further deaths have been reported of people who had tested positive, taking the number of deaths in Wales to 154.
Northern Ireland’s Public Health Agency reported another eight deaths, bringing the country’s total to 56, with a total of 998 testing positive.
Mr Gove announced a series of new Nightingale hospitals would be built in cities across the UK, after the Excel Centre in London’s Docklands was officially opened as a temporary hospital last week.
Analysis by the Intensive Care National Audit and Research Centre (ICNARC) found that the death rate among those admitted to intensive care with COVID-19 has topped 50%.
The centre looked at a sample of 2,249 coronavirus patients and found that out of the 690 patients whose care outcomes were known, 346 – 50.1% – had died, while 344 had been discharged.
The remaining patients, 1,559, were reported still to be in critical care.
As a comparison, just 22.4% of patients admitted to intensive care with viral pneumonia between 2017 and 2019 died of the disease.
The coronavirus infection rate will remain high for “weeks and weeks” if people flout social distancing rules this weekend, a scientist advising the Government has warned.
Professor Neil Ferguson, from Imperial College London, said earlier that while the epidemic was expected to plateau in the next week to 10 days, people’s behaviour was critical to determining what happens next.
His warning followed similar pleas by Boris Johnson and Matt Hancock for people to stick with the social distancing measures and resist the temptation to enjoy the sunshine forecast for swathes of the UK on Saturday and Sunday.
Efforts were under way around the UK to dissuade people from visiting popular spots across the country.
The rise in deaths brought the number of London bus workers have now died with COVID-19 to five, according to a trade union, with Unite regional secretary Peter Kavanagh calling it a “terrible tragedy”.
Earlier, it was announced that up to 4,000 prisoners in England and Wales are to be temporarily released from jail in an effort to try and control the virus’s spread.
Despite the London no longer being the worst area for deaths, pressure on health services continued with Watford General hospital telling people not to attend A&E until further notice, even in an emergency, and to visit other nearby hospitals or seek advice through the 111 helpline.