G20 summit Saturday in a first for an Arab nation, with the virtual forum dominated by efforts to tackle the coronavirus pandemic and the worst global recession in decades.The two-day meeting of the world's wealthiest nations comes as President Donald Trump refuses to concede a bitter election and campaigners criticise what they call the G20's inadequate response to the crippling economic crisis.World leaders will huddle virtually as international efforts intensify for a large-scale roll out of coronavirus vaccines after a breakthrough in trials, and as calls grow for G20 nations to plug a $4.5 billion funding shortfall.Amid a raging pandemic, the summit -- usually an opportunity for one-on-one engagements between world leaders -- is.