Children under 12 should be exempt from the “rule of six”, the Children’s Commissioner for England has said.
Anne Longfield told ministers that children should not be counted in limits on gatherings of more than six people to let families spend time together.
She also said under-12s should be allowed to play with their friends from different households – exempting them from bans on household mingling.
Boris Johnson has faced pressure to relax restrictions for children as the rules in England mean even babies are counted in measures preventing seven or more people from socialising together.
Exemptions are already in place in Wales and Scotland for children under 11 and under 12 respectively.
In a new report, the Commissioner said children had been overlooked in efforts to stop the spread of coronavirus and urged ministers to put their interests first if there is another national lockdown.
She also called for a “Nightingale moment” for children, with a package of support including boosts to welfare for hard-up families, catch-up programmes at school and delays to next year’s summer exams.
The first six months of lockdown “compounded existing inequalities” for 2.2million vulnerable children in England, the report found.
Youngsters who have missed months of school, are struggling with their mental health and facing tough home lives deserve the equivalent of huge efforts made to build Nightingale Hospitals at the start of the pandemic, it said.
The report found 41% of children are more stressed about their schoolwork and exams since schools closed in March, while many felt lonely and isolated from their friends.
“Children have fewer health risks from Covid-19 and yet they have suffered disproportionately from the nation’s efforts to contain the virus,” Ms Longfield said.
“Unless the Government acts now, Covid-19 is in danger of becoming an inter-generational crisis, with the impact of the economic fall-out on parents determining the future prospects of their children.
“This would decimate the Government’s ability to level-up opportunities across the country in the way the Prime Minister has repeatedly promised to do.”
Javed Khan, chief executive of Barnardo’s, said the “negative effects” of lockdown could “last a lifetime” for vulnerable youngsters.
“Barnardo’s has consistently said that we must do more than just recover from the crisis – it must be a catalyst for systemic change to a system that was already failing far too many children long before Covid-19 hit,” he said.
A Government spokesperson said: “Throughout the pandemic, we have taken action, including introducing the rule of six, to get the virus under control and to avoid the need to introduce any stricter measures.
“Supporting children and their wellbeing has been central to our coronavirus response, including getting pupils back to school.
“We have also invested significantly in charities working with vulnerable children and our £1 billion Covid catch up fund will help tackle the impact of lost time in education.”