That specific source is not the only one stating those numbers. Here is Angela Merkel saying as many as 70% [1]. Here is another doctor saying 40% [2] (sorry there is an autoplay video on this site).

[1] - https://www.bbc.com/news/world-us-canada-51835856

[2] - https://www.wbaltv.com/article/what-percent-of-people-in-the...