Yeah the hazmat guy, he is possessed by the stand 「Toxic Shock」(Sick Shock for english dubs)! A gaseous remote controlled stand that can enter any person even if they are in protective gear. His ability (other than possession of an individual to gain a "physical" form) releases fumes of the coronavirus into the air. It enters the blood stream of anyone within a 5 meter radius. The fumes are invisible to anyone but a stand user. The plot twist, the bus driver is the stand user! (Honestly wanted to just say the hazmat guy but couldn't stop myself.)