就在上面提到的链接里：
What is the reason for the change?
In consultations with global expert networks and Member States, WHO has received feedback that applying the initial recommendation of two negative RT-PCR tests at least 24 hours apart, in light of limited laboratory supplies, equipment, and personnel in areas with intense transmission, has been extremely difficult, especially outside hospital settings.
With widespread community transmission, these initial criteria for SARS-CoV-2 posed several challenges:
- Long periods of isolation for individuals with prolonged viral RNA detection after resolution of symptoms, affecting individual well-being, society ,and access to healthcare.
- Insufficient testing capacity to comply with initial discharge criteria in many parts of the world.
- Prolonged viral shedding around the limit of detection, having negative results followed by positive results, which unnecessarily challenges trust in the laboratory system.
WHO还特意加了一句：
Countries may choose to continue to use testing as part of the release criteria. If so, the initial recommendation of two negative PCR tests at least 24 hours apart can be used.
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