Six more JCG pupils and another three Victoria College students have tested positive for coronavirus.
It's understood the affected JCG students are in Year 11.
The class was sent into isolation last Thursday when one girl in the class tested positive.
The affected students at Victoria College have also been isolating at home since last Thursday.
Latest figures show there are 115 known active cases of Covid-19 in the island.
Among the latest to be confirmed was another Victoria College student (the second case at the school) and primary age child at De La Salle.
The classes both boys were in have been asked to isolate at home.
The schools remain open on Public Health guidance.

Man in hospital after serious assault at Havre Des Pas festival
Channel Islander abandons Bordeaux as the flames 'arrive at the city's gates'
Nowacki wins Jersey’s first Commonwealth Games medal in 36 years
Thousands expected at Havre Des Pas Festival this weekend
Commonwealth Games: Nowacki into 100m breaststroke final
Channel Islands face 'physical' Poland test
Price of heating oil and other fuel increase by more than half in a year
Man jailed for importing nearly £600k worth of cannabis in bumpers of his car