London | British Prime Minister Boris Johnson has become the first world leader to come down with COVID-19, but he vowed to continue leading his country's "coronavirus fightback" during his seven-day self-isolation in Downing Street.

The pitiless pandemic also claimed two of his key lieutenants, putting most of his inner sanctum out of action. Health Secretary Matt Hancock has tested positive and chief medical officer Chris Whitty is showing symptoms, sending both into a week-long isolation as well.