Not sure how you're calculating 0.3%, but the tests were taken April 19-28. So by the end of March, 22.7% of people were INFECTED, but we know that it takes a median of 21 days to die from COVID-19 once infected (with a long tail)
So, most people who were infected in late March would, if they were going to die, be dying mid-April. By the end of April, around 75% of the deaths from Feb/March infections should've happened