The common denominator is Frankfurt. Any sentient being would be suggesting that the hotel is the problem, not the crew who have tested positive. It has been shown time and again in places like Australia and NZ where hotels have been used for quarantine that they are unsuited to providing a covid free environment to "inmates". Simple questions have not been answered. Has the hotel had its ventilation upgraded? Do hotel staff wear PPE when delivering food to rooms? Are rooms, hallways and shared spaces properly disinfected? Are all hotel staff fully vaccinated? Are crew transport drivers fully vaccinated? This is an aerosol transmitted virus that doesn't pay heed to keycards, single entry or otherwise. The Delta strain has shown that the virus cannot be eliminated and the only solution is extremely high vaccination rates and learning to live with it. The current policy being adopted by the HKGov and China as a whole is counterintuitive and doomed to fail...both in protecting people and allowing businesses to operate. The quality of crew hotels has deteriorated consistently over the past decade, to the extent that the company is now , in this COVID world, putting crews at risk of catching COVID and/or suffering a complete mental breakdown.