【明報專訊】Hong Kong and Singapore are both small, highly open economies with similar social conditions and levels of development, and they are currently facing relatively similar situations concerning the pandemic and the fight against it. The agreement was the first for both regions and carries important significance. However, there remain many uncertainties over whether cross-border travel can return to normal. The concept of a "travel bubble" is theoretically feasible, but if we look at the experience of different parts of the world in attempting it over the past few months, we can see that almost none of the experiments has been successful.