Britney Spears has received her first dose of the coronavirus vaccine - and she wasted no time in telling her Instagram followers.Sharing a video on Thursday, the singer reassured her followers as she took the jab alongside her boyfriend, 27-year-old personal trainer Sam Asghari.MORE: Britney Spears conservatorship to be explored in brand new BBC documentaryWATCH: Britney Spears receives COVID vaccine with beau Sam Asghari"Got the COVID vaccine...