When to stop isolation and transmission-based precautions for COVID-19 patient and for person who exposed to COVID-19 according to Centres For Disease Control and Prevention and Fighting Against Coronavirus guidelines (an update):
According to Centres for Disease Control and Prevention guidelines, isolation and transmission-based precautions can be stopped according to the followings:
For person who exposed to COVID-19: the person should have 2 weeks since exposure if no symptoms developed, for asymptomatic patient: the patient should have at least 10 days since the first positive PCR test result or if there have been a total of two negative PCR tests from at least two consecutive respiratory specimens collected at least 24 hours apart or more and for symptomatic patient: the patient should have no fever and the respiratory symptoms (cough, shortness of breath and else) are improved for at least 3 days and there have been at least 10 days since the symptoms started or there have been a total of two negative Polymerase Chain Reaction (PCR) tests from at least two consecutive respiratory specimens collected at least 24 hours apart or more.
According to Fighting Against Coronavirus guidelines (which is developed by me, taken into account the Centres For Disease Control and Prevention guidelines, the recovery time for COVID-19 patient according to WHO and the severity of symptoms), isolation and transmission-based precautions can be stopped according to the followings:
For person who exposed to COVID-19: the person should have 2 weeks since exposure if no symptoms developed, for asymptomatic COVID-19 patient: the patient should have at least 2 weeks since the first positive PCR test result or if there have been a total of two negative PCR tests from at least two consecutive respiratory specimens collected at least 24 hours apart or more, for patient with mild or moderate symptoms: the patient should have at least 2 weeks since the symptoms started and until all the symptoms are completely resolved or until the fever is resolved, the respiratory symptoms (cough, shortness of breath and else) are improved and there have been a total of two negative PCR tests from at least two consecutive respiratory specimens collected at least 24 hours apart or more and for patient with severe or critical symptoms: the patient should have at least 6 weeks since the symptoms started and until all the symptoms are completely resolved or until the fever is resolved, the respiratory symptoms (cough, shortness of breath and else) are improved and there have been a total of two negative PCR tests from at least two consecutive respiratory specimens collected at least 24 hours apart or more.
The Fighting Against Coronavirus guidelines recommend home isolation and transmission-based precautions for person who exposed to COVID-19, asymptomatic COVID-19 patient and COVID-19 patient with mild symptoms, hospital isolation and transmission-based precautions for COVID-19 patient with severe or critical symptoms and home or hospital isolation and transmission-based precautions for COVID-19 patient with moderate symptoms according to the clinical situation.

The immunocompermised patient with COVID-19 may have more prolonged time for shedding the virus.
Detecting viral RNA via PCR does not necessarily mean that infectious virus is present.
Although Fighting Against Coronavirus Guidelines may reduce most of viral transmission in comparison to Centres For Disease Control and Prevention guidelines but may not completely prevent viral transmission since there have been reports of prolonged time for shedding the virus from infected patient, so the decision to stop isolation and transmission-based precautions should be made in the context of local circumstances.
Both guidelines may subject to change if a new information about COVID-19 comes.

Dr.Mazin Muzamil Abdel-Ghaffar