Just lile there are probably hundreds of thousands of people in the UK who have it and go about thier normal daily lives but as they dont have symptoms they don't get a test. Its the same with every single desease or virus that exists, you only know if you have got it if you have systems and get a test for it. This is why the world has to accept it and move on sooner rather than later, it's inpossible to isolate every single person who has it and be able to live any sort of life.