OSHA estimates 6,500 lives will be saved by the mandate over six months or ~0.02% of the U.S. population. While there is uncertainty in these estimates, they are confident hundreds of lives will be saved. At first glance there seems to be many less politically fraught avenues of improving public health.
OSHA was created through the law, and they have the authority to change what they deem necessary whenever they want. Their decisions can be challenged in court (as this rule has been), but it’s not “executive order” per se. Congress gave the President the power to do this.
A vaccine mandate by OSHA, however, is unprecedented, and I can’t speak on how successful it’ll be and whatever unintended consequences it may have
> they have the authority to change what they deems necessary whenever they want.
I think the courts have a history of disagreeing on that point. Not enough, mind you, we've seen an unprecedented expansion of federal powers, but they have been ruling some of the more extreme executive orders unconstitutional.