Children aged 12 and over must wait 12 weeks after any Covid-19 infection before they get vaccinated.
UK regulators have decided on the delay because of the “very, very small” risk of a little understood side effect of heart inflammation.
Health officials say current case rates of myocarditis after vaccination among under 18s are around nine per million vaccinations and cases have been “relatively mild”.
However the 12-week rule will lead to significant delays in rolling out the vaccine programme among children.
Around half of school children have had Covid-19 and yesterday’s REACT-1 study showed one in 20 pupils were infected between October 22 and November 4.
The current advice for older people and for people at high risk of Covid-19 - including those aged 12 and over - is that they should wait four weeks between Covid infection and having a dose of vaccine.
But officials said this should be extended to 12 weeks in lower-risk children between 12 and 17.
The guidance comes amid high infection rates among younger age groups.
It is thought that a natural Covid-19 infection in younger people provides them with “at least” three months’ protection and could extend to six months.
On Monday, the Joint Committee on Vaccination and Immunisation (JCVI) said 16 and 17-year-olds could book their second Covid-19 vaccine 12 weeks after their first.
But the UKHSA said that should teenagers in this age group be infected with Covid-19 after their first dose, they should then delay the second dose until 12 weeks after the infection.
