Your travel insurance T&C must specifically mention, Covid coverage including this and that and the coverage amount. If possible not mandate, get the insurance company to come out with a letter on u been covered for covid with $X.
Hotel, just book directly with any SHA++ hotel, importantly must include PCR test and transportation pick up from airport. The hotel will send u the confirmation and details.
As for V-cert, u can download easily.
PCR in SG within 72hrs by any MOH approved clinics.
Apply early for Thaipass, mine took about 10 days before it was approved. If fails, u need to amend and upload the information which will take another few days to approve.
Take note, u need to purchase a VTL air ticket if you wish to return to SG. Check out Safetravel for more information and requirements to enter SG.
Good luck, I should be heading to BKK again end of Feb or early March. Will go thru the above processes again
