As most of our readers will be aware, Singapore’s first leisure travel ‘green lane’ took the form of a so-called ‘Air Travel Bubble’ arrangement to and from Hong Kong, first announced in October and scheduled to kick off on 22nd November, initially with one then two flights per day in each direction.
It won’t come as headline news that the plan was scrapped just 16 hours before the first flight was due to depart, as a consequence of Hong Kong’s rising COVID-19 case numbers, in what looked to be the start of a ‘fourth wave’ of infections in the city.
The fourth wave is here
If you haven’t been keeping up with the daily case totals in Hong Kong over the week that’s passed since the ATB was postponed, it’s not great news.
The city’s fourth wave is definitely here.
Yesterday Hong Kong recorded 115 new COVID-19 cases, the first time the 100 level has been breached since 2nd August 2020.
Hong Kong daily new COVID-19 cases

Data: Hong Kong CHP
For those hoping this latest spike in cases might replicate the smaller ‘second wave’ in March and April, the graph speaks for itself. The new rise looks set to be at least as bad as Hong Kong’s more severe ‘third wave’ in July and August.
Only unlinked cases impact the ATB
New COVID-19 cases themselves don’t have a direct consequence on the ATB. When the bubble was agreed, a ‘circuit breaker’ was adopted, relating to the trend in unlinked cases in either city.
The, policy, which was designed to suspend the ATB once it was already running, required that it be put on hold for two weeks if the seven-day moving average of the daily number of unlinked COVID-19 cases exceeded five in either Singapore or Hong Kong.
Flights would then become non-ATB services after a 48-hour notice period, so that if you were already on your trip there was a window of opportunity to return to Singapore (or Hong Kong) on an ATB flight without any quarantine / SHN requirement.
The arrangement would then resume only if the seven-day moving average on the last day of the suspension period fell to five or fewer.
Hong Kong daily unlinked cases
Date | Unlinked cases |
7-day average |
11 Nov | 3 | – |
12 Nov | 6 | – |
13 Nov | 2 | – |
14 Nov | 1 | – |
15 Nov | 1 | – |
16 Nov | 0 | – |
17 Nov | 1 | 2.00 |
18 Nov | 1 | 1.71 |
19 Nov | 2 | 1.14 |
20 Nov | 9 | 2.14 |
21 Nov | 13 | 3.86 |
22 Nov | 11 | 5.29 |
23 Nov | 8 | 6.43 |
24 Nov | 10 | 7.71 |
25 Nov | 16 | 9.86 |
26 Nov | 13 | 11.43 |
27 Nov | 17 | 12.57 |
28 Nov | 27 | 14.57 |
29 Nov | 24 | 16.43 |
Data: Hong Kong CHP
As we know, Hong Kong and Singapore decided to postpone the ATB just before this threshold was reached, as it became increasingly obvious the ‘circuit breaker’ conditions would be triggered in the first few days.
“The Government of the Hong Kong Special Administrative Region (HKSAR) announced today (November 21) that in view of the recent epidemic situation in Hong Kong, the Governments of HKSAR and Singapore have decided to defer the inaugural flights under the Hong Kong-Singapore Air Travel Bubble (ATB) for two weeks.”
Government of Hong Kong SAR
That was a good call, since you can see from the table above the 7-day average of unlinked cases would have exceeded the threshold on 22nd November, it’s first day of operation!

Currently, the 7-day average is running at 16.43, more than three times the threshold.
Unlinked cases aren’t as bad this time
In Hong Kong’s ‘third wave’ of infections, the 7-day rolling average of unlinked COVID-19 cases in the city would have breached the ATB’s limit of five on 12th July 2020. It would not have fallen below five again until 1st September 2020, 52 days later.
That’s a seven-and-a-half week suspension period, had the ATB been in operation.
Looking at the first graph of ‘pure’ case totals, you’d logically assume it will be no different this time round, potentially pushing a new ATB inaugural into mid-January 2021.
There is a difference this time round though – unlinked cases aren’t as high.
Hong Kong unlinked cases 7-day average

Data: Hong Kong CHP
As you can see despite a similarly rapid rise in case numbers, there were far more unlinked cases in the third wave at this stage compared to this latest outbreak, potentially helped by a new contact tracing app LeaveHomeSafe, which launched in mid-November.
While it’s obviously too early to reach a conclusion on that basis, it does provide some hope that the ATB postponement may not be as long as the 52 days we would have endured had it been running in July and August.

Realistically though, with numbers still rising at the time of writing, even if a peak is soon reached and the totals begin declining again it looks to be late December at the earliest before we’ll consistently see the unlinked case average drop below 5.
That means very little chance of taking a Christmas or New Year trip to Hong Kong under the ATB, and short of a sudden turnaround this week, we expect the authorities will actually put on ice until next year.
Currently, Singapore Airlines is selling tickets on its Hong Kong flights from 23rd December 2020.
Could Singapore forge a different ATB first?
Given the direction in case numbers coming out of Hong Kong and the distinct possibility of a lengthy suspension of the ATB as a result, one option for Singapore might be to turn to other countries for its inaugural leisure travel bubble arrangement.
There are very low case numbers in Thailand, Vietnam and Taiwan, for example, with the latter seeing no domestic infections since 12th April.

Unfortunately there would likely be political sensitivities putting some of these potential countries ahead of the ATB with Hong Kong.
In some cases these places may also have been waiting to see how the inaugural ATB worked out, before adopting one themselves. Becoming the first to try it now probably isn’t high on their agenda, given the ill-fated launch of the Hong Kong ATB.
Summary
With rising COVID-19 case numbers in Hong Kong in the city’s ‘fourth wave’ of infections, the 7-day unlinked case average has been progressively rising over the last week or so and is now more than three times the threshold for operation of the Air Travel Bubble.
While on the face of it this fourth wave looks set to be at least as bad as the recent one, a higher proportion of cases are being linked this time round, giving us at least some hope that we may not be looking at a two-month suspension of the ATB.
Nonetheless a new inaugural date before Christmas looks unlikely, and we expect the postponement will probably be extended until early 2021 given the uncertainty, unless cases start to decline rapidly this week.

Representatives from the Hong Kong and Singapore governments are due to provide an update on the ATB in early December.
Sadly, it’s beginning to look obvious what they’ll have to say.
(Cover Photo: Sorbis / Shutterstock)