There was a confirmed case of COVID-19 at the clinic and all 150 individuals connected are being contacted.
The fact that Canadian Blood Services keep records of all involved makes the process go smoother.
People are being asked to isolate and monitor for symptoms but not get tested immediately.
Similar clinics scheduled for this weekend were cancelled.
As of Friday there were 16 active cases in the municipality.
The number of active cases in Sarnia-Lambton stands at 6.