Can I still buy isolation allowance after flying a faster plane automatically?

I'm about to board the plane, so I can't buy isolation allowance.

The meaning of air ticket isolation allowance insurance is simply that you will be compensated if you buy an air ticket but are isolated at the airport. Generally speaking, with the relevant responsibilities of COVID-19, different insurance companies have slightly different responsibilities for similar products, some of which may only include air tickets, while others may cover trains.