I see this as a positive development for a lot of reasons.
For one, establishing an international standard. Anyone who's traveled to undeveloped or underdeveloped regions has experienced carrying a cardstock vax card for production at entry ports.
Second, a large group of the population is wary of government sponsored vax passports, particularly in the US. But, to return to a life where we can do things like go to ball games and concerts, it's going to be a necessity. Too many people will forge or out and out like about their status, which is unacceptable. People might be more inclined to trust an industry group like the IATA than their government.
Finally, it will encourage more people to get their vaccine. I know a LOT of people have a hesitancy to do so. I understand the large list of reasons why. I certainly don't agree with them all.
I've had both doses of the Moderna vax. Our work got it for us early as we are front line essential, so I had my second shot back in February. My wife gets her second this Saturday. She was a bit hesitant, as was I at first. One of my doctors participated in the Moderna trial as a recipient. After speaking with him, I decided to go ahead with it.
Me and my wife both had minimal side effects. I had a sore arm and felt lousy the next day. She as well, but a bit tired. I had no side effects to the second shot. I was also previously infected with COVID and (obviously) survived.
I would encourage everyone who has not, and has access to get the vax. A large group of my co workers had it at the same time, and only 2 had reactions that were similar to a flu shot reaction.