The principal of the Catholic Ursuline Primary School in Blundellsands, near Crosby, has sent a letter advising parents and carers of affected children what to do.
Parents of students at a Sefton Elementary School were told that their child must isolate themselves for 14 days after a confirmed positive case.
Any child in close contact with a person must isolate themselves for 14 days.
“We followed the national guidelines and found that your child was in close contact with the person concerned.
The letter states: “We have been informed that we have a confirmed positive case of coronavirus (Covid-19).
It is not known whether the positive case is a teacher, another member of staff or a student of the school.
“In accordance with national guidelines, your child must stay at home and isolate himself or herself until and including Monday, October 26 (14 days after contact).
“If your child is well at the end of the 14-day period of self-isolation, he or she may return to his or her usual activities.
More than 100 schools in Merseyside have reported positive cases of coronavirus since students returned last month.
This means that thousands of children in the region are now in self-isolation.
The government has placed Liverpool City in the most severe category as of today after a sharp increase in coronavirus transmissions in recent weeks.