It looks like a decent chunk of Ontario's COVID-19 tests have been inaccurate since April. Based on information revealed by CBC, approximately 700 positive tests went unreported because the data was sent to the wrong hospitals. As a result, the information was not revealed to 12 Public Health Units in Toronto, York and Peel Regions.In fact, Public Health Units only found out about the cases this past weekend.A majority of the positive results came from William Osler's drive-thru assessment centre in Etobicoke, a spokesperson for Ontario Health revealed to CBC.Now, officials are working to trace thousands of people who could have come into contact with positive cases. "Following a thorough investigation, it was determined that COVID-19 positive test results from one of the COVID-19 provincial testing laboratories and used by the William Osler Health System assessment centre had not been reported to 12 local Public Health Units where the cases reside," said a spokesperson for Ontario Health.According to CP24, officials say that the people who tested positive for COVID-19 would have had access to the test results online. Narcity has reached out to Ontario Health for confirmation.\nAccording to CBC, the wrong test results were sent to two different hospitals, each of which did not know what to do with them. Their staff was under the impression that it was the responsibility of the other hospital to send in the information, according to the unnamed source that spoke with CBC. However, public health officials are saying that it was William Osler who was responsible for passing on the information, not the hospitals."We were made aware of William Osler's gap in reporting to public health units this past weekend," said Hayley Chazan, a spokesperson for Ontario Health Minister Christine Elliott, in an email to CBC News on Monday.\n"Over the weekend, public health units began identifying and confirming with patients, starting with those who had been tested within the last 14 days, to ensure contact tracing and case management began," said Ontario Health. "All parties are working to ensure this situation does not happen again, and steps taken to prevent re-occurrence."\nOntario's cases have been misreported once before.\nJust a couple of weeks ago in May, it was reported that 87 cases in Ontario were omitted from the case count due to a data glitch.