It's obvious that the CDC card we Americans get after vaccination are going to be very important for international travel among other things. (Some sports stadiums will also only open to people who have been vaccinated.)
Originally, I suggested laminating the card but that also means the cards could get damaged. However, waterproof, zip cardholders are now available for the CDC cards. I just ordered the ones I mention below but haven't received them yet. It may be something to help protect the card from damage. I'll report back once I get them to make sure they work.
(There are numerous different ones for sale. I just happen to choose this one. Choose whichever one you prefer.)