Ex-adviser Kellyanne Conway, campaign manager Bill Stepien and two Republican senators - Mike Lee and Thom Tillis – have also tested positive for coronavirus
"At no point has Russia been under threat from Nato" says White House Press Secretary Jen Psaki, in response to President Putin putting Russia's nuclear forces on "special alert"
The potential new vaccine for Covid-19 has been making headlines around the world
Here’s what you need to know about what it might mean for you #BBCYourQuestions
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