The announcement of the Vaccinated Travel Lane scheme, which will start with Brunei and Germany, is definitely great news for Singaporeans and the travel industry, after many months of the border being closed (S'pore eases border measures, launches vaccinated travel lanes, Aug 20).

However, there is a potential loophole in this arrangement.

If a Singaporean visits Germany under this scheme, he is required to have visited only Singapore and Germany in the last 21 days before he is allowed to travel back to Singapore.

How do the authorities ensure that? Would it be possible for someone to arrive in Germany, take a train to visit another European Union country, then return to Germany for his flight back to Singapore? His passport would not reflect any country other than Germany since there are no border controls in Europe's passport-free zone for those travelling by train.

Ng Kok Thye