Its been 15 days since i tested positive for covid. its been 14 days since my sister tested positive for covid. my parents are worried we might still be able to pass them the virus. is that possible? also, why does covid test say positive for 3 mo?

The PCR test is highly accurate. If you are still positive, there is a detectable viral load. If the virus is able to replicate, then you are still contagious. Other testing detects the antibody response, but this is less useful . If you are symptom free, it is unlikely that you are still contagious, but a PCR test is recommended. Watch for shortness of breath and prolonged cough and fever.

A PCR test can give a positive result from dead virus in the nose. If you have not been febrile for more than 24 hours without taking fever reducing medication and have been more than 10 days from testing positive, you are unlikely to be infectious. Get your parents vaccinated. You parents could an oral medication for Covid. You and your sister get vaccinated despite having had an infection.