Unsaid here is what are the odds of a twice vaccinated person (With Pfizer, for example) of getting a breakthrough infection. I've gone through the CDC and some of the more trusted entities and come up with a 1 in 5,000 or so chance of getting the disease. No doubt a lesser probability after a booster shot, and even less if a mask is worn in higher risk situations. It's all rather iffy, and using projected Israeli, Danish, Swedish or other testing and back fitting to the US is not ideal, but lots better than nothing.