St Francis Xavier’s College at Hamilton is closed for deep cleaning after a student tested positive.
The teenager is a close relative of a 15-year-old St Pius X Adamstown pupil and a man in his 20s who tested positive earlier in the week.
Hunter New England Health is continuing to investigate the source of infection for all three cases.
Anyone who attended SFX on Monday, Tuesday or Wednesday should be on the lookout for symptoms and get tested immediately should any respiratory symptoms or fever occur.
“All close contacts of the teenager are being notified and are required to seek testing and isolate for 14 days, regardless of their test result,” HNEH said in a statement.
The school notified parents on Thursday night and said the campus would be closed on Friday.
SFX is a senior Catholic college for year 11 and year 12 students, with 941 students and 125 staff.