Boris Johnson has stressed grandparents should not be called upon to look after children amid the coronavirus outbreak.
The prime minister announced on Wednesday schools will close from Friday afternoon until further notice.
With the virus emerging at the end of last year, no one has immunity to the previously-unknown strain.
While anyone can catch the infection, children are not generally becoming seriously unwell.
Chief scientific adviser Professor Patrick Vallance stressed schools are safe and will be closed to “put some brakes on the illness”.
The vast majority of deaths are occurring in the elderly, making grandparents unsuitable babysitters.
Latest coronavirus news, updates and advice
The coronavirus emerged at a seafood and live animal market in the Chinese city Wuhan at the end of last year.
It has since spread internationally into more than 150 countries across every inhabited continent.
Since the outbreak was identified, more than 211,800 cases have been confirmed worldwide, of whom over 83,000 have “recovered”, according to John Hopkins University data.
Cases have been plateauing in China since the end of February, with the epicentre of the pandemic shifting to Europe.
Italy alone has had more than 31,500 confirmed cases and over 2,000 deaths.
In the UK, more than 2,600 people have tested positive for the virus, of whom 104 have died.
Globally, the death toll has exceeded 8,700.
Why should elderly people not look after children amid the coronavirus outbreak?
After facing criticism for doing too little to stem the coronavirus outbreak, Boris Johnson has announced schools in England will close indefinitely from Friday.
This follows similar announcements in the rest of the UK.
“The most vulnerable” children and those whose parents are “key workers” – like NHS staff – are the exception and will continue to go to school.
Professor Vallance stressed schools are “not dangerous places”, with this extreme measure “now important to protect NHS capacity”.
Experts have previously supported Johnson’s decision not to close schools, worrying this could impact the health of older people.
With schools now set to close, some still do not support the move.
“I’m concerned about the impact of school absences and school closures,” said Dr Bharat Pankhania from the University of Exeter.
“I suggest we urgently test for [the coronavirus’] presence or absence, and close those [schools] where it is present, rather than closing all schools.”
With total isolation not yet enforced, Professor Stephen Reicher worries “informal swaps” may occur between parents looking after young children.
“For older children the key issue is to give them resources so they have something to do at home and still stay in contact with their friends,” he said.
“And ensuring the provision of internet facilities to keep people connected along with interactive platforms and games to keep them entertained at home will be a key contribution to helping people, especially young people, stay at home.”
The most vulnerable in society, people over 70 or those with pre-existing health conditions, are expected to be told to self-isolate entirely for up to four months in the near future.
Scientists from the Chinese Center for Disease Control and Prevention previously published information on the 44,672 confirmed cases as of 11 February.
Results suggested the highest fatality rate was in those aged 80 or over, where 14.8% did not recover.
In patients up to 39, the death rate was 0.2%.
No fatalities were reported in children up to nine years old.
A human’s immune system is thought to become less “sharp” with age.
“The reason for this is multifactorial,” Professor Janet Lord from the University of Birmingham previously said.
“Part of it is exaggerated inflammation caused by the response of the immune system and also the aged lung which is less resilient to damage induced by infections.”
For the most part, experts agree self-isolation among the elderly is “sensible”, but worry about the psychological impact of spending so much time alone.
With grandparents “out of the question”, some worry parents may be “forced” to give up employment in order to be there for their children.
“Parents may need to miss work leading to loss of income and wider disruption,” said Dr Charlotte Jackson from University College London.
“Dealing with these issues will be harder for some families than for others.”
What is the new coronavirus?
The new coronavirus is one of seven strains of a class of viruses that are known to infect humans.
Others include the common cold and severe acute respiratory syndrome (Sars).
The new coronavirus tends to cause flu-like symptoms initially, such as a fever, cough or slight breathlessness.
While most cases are mild, pneumonia can come about if the infection spreads to the air sacs in the lungs, causing them to become inflamed and filled with fluid or pus.
The lungs then struggle to draw in air, resulting in reduced oxygen in the bloodstream and a build-up of carbon dioxide.
The coronavirus has no “set” treatment, with most patients’ immune systems fighting off the virus naturally.
In severe cases, hospitalisation may be required if a patient needs “supportive care”.
This may include ventilation while their immune system gets to work.