Professor from John Hopkins University claims that number of US Covid-19 cases is higher than announced

Dr. Marty Makary from the John Hopkins University claims that for every person that has been positively tested for the coronavirus, multiple untested but infected people are out there. He thinks that the US has between "50,000 and half a million cases". Even his lowest estimation is way higher than the official number of over 1,600 confirmed cases. He also criticizes the CDC - the Centers for Disease Control and Prevention - for not rolling out the testing fast enough and even using the wrong testing system.