Getty UK Prime Minister Boris Johnson will remain in hospital "as long as necessary" on Monday after being admitted on Sunday for "persistent symptoms of coronavirus." Johnson tested positive for the coronavirus ten days ago and continues to experience a high temperature. Aides have reportedly become "increasingly worried" about the prime minister's health in recent days due to his appearance and symptoms of the virus. Johnson was "more seriously ill than either he or his officials were prepared to admit," according to the Guardian, who report a source suggesting that Johnson "was being seen by doctors who were concerned about his breathing." Visit Business Insider's homepage for more stories. UK Prime Minister Boris Johnson will remain in hospital on Monday after experiencing "persistent symptoms of coronavirus," ten days after first testing positive for it. The prime minister was admitted to hospital on Sunday on the advice of his doctor after continuing to exhibit a high temperature, Downing Street indicated.See the rest of the story at Business InsiderNOW WATCH: A law professor weighs in on how Trump could beat impeachmentSee Also:How America's decimated pandemic response capabilities led to one of the worst coronavirus outbreaks in the world'It is everywhere already': Fox News hosts amp up the pressure on Trump to give up on coronavirus lockdowns and reopen the economyThe Trump administration issued a new rule that blocks guaranteed paid sick leave for 75% of American workers