To the frustration of local and international business, Hong Kong’s border with the mainland remains closed because the city’s Covid-19 control measures are not up to Beijing’s strict requirements. As a result, there has even been talk of permanent damage to the city’s status as an international city . Hong Kong has reported only one locally acquired case of Covid-19 since August 17. In that regard it has complemented the mainland’s zero-tolerance strategy. Naturally, this raised hopes that Beijing would reopen the border to quarantine-free travel. They have been dashed because Beijing remains unhappy with the city’s infection-tracking mechanism and its many quarantine exemptions, aimed at preserving travel and commercial links. So concerned are central government authorities that the exemptions could leave the mainland exposed, they have demanded they be severely curtailed if the border is to reopen. Chief Executive Carrie Lam Cheng Yuet-ngor has foreshadowed compliance. But there is still no guarantee of reopening, given questions whether Hong Kong’s tracing system is up to standard. It would only take one more local case to prompt Beijing to rethink. As Hong Kong’s sole delegate to National People’s Congress Standing Committee Tam Yiu-chung has said, “the mainland attaches great importance to unknown cases”. Indeed, Beijing barred Tam from attending a regular meeting of the committee not long after Hong Kong reported the isolated case. In a further move to assuage Beijing’s concerns about Hong Kong’s handling of the pandemic, recovered Covid-19 patients will have to spend 14 days in quarantine in a separate facility after discharge from hospital. As to whether Hong Kong is taking these measures only in the interests of public health or because they are what Beijing wants, Lam gave a revealing answer . Covid-19 health code: how Hong Kong can reopen the mainland border “In order to resume some quarantine-free travel with the mainland, we have to ensure that our anti-Covid-19 practices are more in line with the mainland, so that the mainland authorities will have the confidence to enable Hong Kong people to go into the mainland without being subject to the 14-day plus seven-day quarantine”. The government’s priority for reopening the border is understandable. The question now is whether exemptions are ultimately the main obstacle. This follows news that the contact-tracing app “Leave Home Safe” is to become mandatory for visiting Hong Kong government premises from today, prompting speculation this would pave the way for a link with the mainland health-code app for the resumption of quarantine-free cross-border travel. But mainland authorities apparently are not yet satisfied with the current design of the Hong Kong app. So how mandating it locally can lead to the border reopening is unclear. The government should explain how it can be done.