The US can't even handle the first 1a and 1b phase, I doubt normal people here will be vaccinated by the fall. Not to mention being vaccinated doesn't mean you're no longer a carrier. I have no dog in this fight since I completed my trips long ago but I want to level set people since I'm privy to some high level health decision in Vietnam. No commercial flight until q4 is the standing directive. You can enter under the experts/business exception but still have to quarantine for 2 weeks. Good luck.