What you're proposing is highly experimental and probably wouldn't work. There's no single country in the world that has been able to restrain the sars2 virus despite spending millions trying to do so.
Vietnam isn't a paragon of wealth and competent administration today, there is no good reason our public health departments should not have been able to perform equally or better than their equivalents in Vietnam.
We have mandatory two week quarantine for all arivals, stores lose their business licenses if they let anyone in without a mask. Schools, cinemas, gyms, clubs are all closed.
We’re hoping things will open up again in two weeks.