Isolation and accompanying precautions for COVID-19 patients should be continued until they lose infectiousness. Longer isolation is ideal to avoid (falsely) ending isolation of infectious patients; however, (unnecessarily) prolonged isolation negatively impacts mental/physical health of those isolated patients. Better understanding on when to end isolation of COVID-19 patients is warranted. Because infectiousness is associated with viral load, PCR test-based approach has been used in determination of ending isolation. The purpose of this proposal is to propose and assess test-based guidelines for ending isolation of COVID-19 patients using a virus dynamics model. The mathematical model captures longitudinal viral load change which typically shapes a bell curve. We parametrize the model using longitudinal viral load data collected from COVID-19 patients from published data. Through simulation using the model, we will explore how the PCR test results should be utilized in the context of isolation. Specifically, we will determine the optimal frequency of PCR tests and the number of continuous negative results necessary to be certain that the patient will not produce further transmission. Further, as the virus dynamics is different between patients, the timing of ending isolation should be determined for each patient. Therefore, we plan to develop a web platform to input patients’ viral load data and obtain whether isolation can be ended and when the isolation would be ended for each patient. We expect this project will help both health practitioners and patients think about logistics during isolation and minimize the financial and phycological burden of isolation beyond COVID-19 infection.