Four individuals at the school on Grange Road have tested positive for the novel coronavirus, however an outbreak has not been declared and the building remains open.
A spokesperson for public health said no outbreak was declared because none of the cases are linked to exposures that have occurred inside the school setting.
“At this point, there is no indication of spread within the school,” Danny Williamson said.
In a letter home to parents, Holy Trinity said the building is safe as custodial staff completed cleaning and disinfecting of the school.
Meanwhile, a COVID-19 outbreak continues at Waverley Drive Public School, where one student and two staff members have tested positive for the virus.
Six other schools in Guelph are reporting a COVID-19 case, but all schools remain open.
The University of Guelph is reporting two active cases connected to its campus, but in both, the risk is considered low.