The testing will not tell you if you were infected previously, as the antibody test is not yet available. The test detects COVID19 virus in your body at the time of testing. If you have been exposed and are in the early days of incubating the virus, it might not be detected. https://twitter.com/ottawahealth/status/1264608645825912833">https://twitter.com/ottawahea...

Like with any test, there can be false negatives and false positives, so the result needs to be interpreted in the context of exposure risk.

Also, COVID19 virus particles may be detected for weeks after someone has stopped being infectious. In Ontario, someone is considered no longer infectious to others from 14 days after the onset of their symptoms, or 24hours after symptoms resolve, whichever is longer.