A caring & diligent government would inform you of this, & clearly state the guidelines. Not suggest you can a) take one antigen test & disregard your risk to others, or b) not test at all. Second, we need a federal agency (perhaps the new "Long Covid" group, since the CDC has apparently abandoned its statutory role) that funds #COVID monitoring & actually does it. Federal govt should fund sampling at *every single* #Wastewater treatment plant in the US. There is no reason not to do this.