I'm not especially concerned about getting sick, but I am concerned about the cost and inconvenience after getting a positive pre-flight test to return to the US. If you've had to delay your return what is your experience booking a return flight? Did it cost more than your original ticket price? If so, was it as much as the cost of a short-notice one-way fare? Did the airline work with your and/or take into account that you changed due to not being allowed on your planned flight?