So, here you have it

The good news is that Hong Kong's borders with the mainland won't be closed due to the detection of a single local case as it had been feared that the mainland's zero-tolerance Covid policy might require the border to be closed to quarantine-free travel once a local case was confirmed in the SAR.

The bad news, however, is that anyone keen to travel to the mainland may still be unable to do so even if they are lucky enough to be included in the small daily quota - if they happen to live in the same estate as someone infected with Covid.

It's rather draconian - what does this mean?

If the new travel arrangement had already been rolled out, thousands of Tai Koo Shing residents who were just slapped with a compulsory testing notice would have immediately seen their color change from green to amber under the new cross-border coding system - had they also registered with the new Hong Kong Health Code - even though they did not live in the same block as the infected person.

The Hong Kong Health Code is open for registration this morning and forms an integral part of a quarantine-free border crossing arrangement. It consists of red, amber and green - only those attaining green can travel to the mainland without having to undergo quarantine.

Following the color change, the Tai Koo Shing residents would have been barred.

More serious still, the mainland was reported to have demanded even stricter criteria that went beyond a housing estate.

Both Hong Kong and the mainland were reported to be discussing whether people living within a certain perimeter in the same district of an identified case would have to be flagged too.

While caution is certainly appreciated, could the reported cautious approach be too extreme? The agreement to reopen the borders is meant to be an attempt to enable daily crossings to return to normal over time, but the strict approach is too excessive to achieve the policy purpose.

For example, in the latest Tai Koo Shing incident, a man who lives in Po Shan Mansion left Hong Kong last month for the Czech Republic via Germany, with a negative Covid test before departure.

On his return to Hong Kong, he tested positive and the entire population in Tai Koo Shing was immediately ordered to take a compulsory test because he was in Hong Kong during the incubation period.

If an agreement was to be reached to enlarge the area further in order to keep the border open for quarantine-free travel, a larger number of people would likely have to be flagged amber every time a case is found - although the number of people permitted to cross the border may be as low as 1,000 in the beginning.

Would this antagonize the majority who are shut out of the scheme in the beginning?

The measures must be balanced - and it would be too draconian to flag everybody in the same estate or district.

Amber alert big hurdle in border crossing