SPRINGFIELD — Gov. J.B. Pritzker has tested positive for COVID-19 and is isolating at home, his office announced Tuesday, three days after he spoke at a gathering of Democrats in Tampa, Florida.Pritzker’s press office said he is experiencing mild symptoms and has received the anti-viral medication Paxlovid, a drug that received Emergency Use Authorization from the U.S. Food and Drug Administration in December for individuals at high risk to the effects of COVID-19.The drug, according to clinical trials, reduced …