If football clubs required a reminder that Covid-19 remains a threat to the current campaign, they needed only look at the chaos that ensued at the London Stadium on Tuesday evening.Less than an hour before kick-off in their Carabao Cup encounter against Hull City, Hammers manager David Moyes, defender Issa Diop and midfielder Josh Cullen all received positive coronavirus tests.All three were forced to leave the ground immediately and while West Ham went on to win the third-round tie 5-1, t