Covid-19, Air travel, and Adjusting to Our Changing World!

It all began with our agonizing and shocking 9/11 experience! Over time, we gradually got used to airport security requirements, and we all now get them for granted. And then, we were introduced to the concepts of TSA Precheck, Clear, and Global Entry.
Some of us may not know that entry to many countries, for long, would have required evidence of vaccinations against certain diseases. The most common mandatory vaccination certificate required by many countries in recent years has been for the Yellow Fever. For instance, travelers coming from Yellow Fever infected countries have been required to show evidence of vaccination within the first five days after departing from their countries.
Having said all these, can you guess what are the top two anticipated and required travel documents of our Covid-19 infested world?
Well, here is Dr. E’s prediction: certificate of positive IgG serology or Covid-19 vaccination!
