Biden was in close contact on stage with Trump for 90 minutes. If they follow the CDC protocols; Trump should quarantine for 10 days (October 12) as a positive test; and Biden (if he tests negative) should quarantine for 14 days (October 16); - (conveniently excusing Biden from the October 15 debate, but I digress...).
It’s the height of irresponsibility for Biden to carry on with publicly campaigning now that Trump has tested positive, aften Biden was in close contact with him for a full hour and a half.
Biden just broke his 12 hour Twitter silence so he must have tested negative.