The elastic on my jacket's waist band has been useless for years. For normal working of the hives, it seems to be no problem---it's very rare that a bee comes inside and works its way up and if one does, it's more interested in finding it way out when it reaches the hood. That makes it an easy target for smashing.
When I do more challenging work (like taking off honey) and I'm concerned about a possible "invasion", I simply tie a string or put on a belt around the waist of the jacket to see that it stays impervious to bees.