Can I fly into Thailand with a COVID test done in Australia while stopping over in Vietnam?

@Terary *********

Also, could you be a bit more specific about your experiences because Thailand has definitely greatly relaxed restrictions over the past several months. Last year for instance, even babies needed to have a PCR test before departure and were tested, sometimes brutally, on arrival. This practice has stopped now, with those under 6 not requiring anything, whereas some sources suggest anyone under 18 doesn't need anything as long as they're traveling with their parents.

When did you enter Thailand?

Singapore Airlines doesn't fly to Mexico, so I suspect you entered the US by land (or air, with a different carrier) and then switched to SQ to get to Bangkok. Now SQ involves a change of aircraft in Singapore as well, as there are no non-stop flights from the USA to Thailand.

My flight is on the same airline from the origin through to Thailand.

I am a little bit concerned that they might say something but it's also possible due to the relatively short transit, they might ask for the test in Australia (where I'm flying from) and this won't need to be checked again in Saigon. It could be they might issue both boarding passes at the same time in Australia.