These are patients who had a positive test in April. Most infected people without symptoms or with mild symptoms did get tested in April in the US. We know about 20-40% are asymptomatic, with higher % among younger people. So actual rate based on this study would be upper bounded by 1⁄4 (not 1⁄3) and point estimate closer to 1⁄5. (I also agree with SDM).
These are patients who had a positive test in April. Most infected people without symptoms or with mild symptoms did get tested in April in the US. We know about 20-40% are asymptomatic, with higher % among younger people. So actual rate based on this study would be upper bounded by 1⁄4 (not 1⁄3) and point estimate closer to 1⁄5. (I also agree with SDM).