If your child has symptoms of a respiratory infection and they have a high temperature or do not feel well enough to come to school or carry out normal activities, they should stay at home and avoid contact with other people until they no longer have a high temperature or until they no longer feel unwell.
If they have taken a Covid-19 test that returned a positive result, they should please stay at home and avoid contact with other people for 3 days after the day they took the test. The suggestion is that most young people with Covid-19 will no longer be infectious to others after 3 days. However, everyone is different and you should continue to follow this advice until your child feels well enough to return to school again and no longer has a high temperature.
Adults and young people over the age of 18 should also follow this advice, although the number of days for isolation is 5 rather than 3.
More information and guidance can be found here.