it is possible that something contagious was engineered and released, even inadvertently (then). In the end of 2019/early 2020 several people in my office came down with a "terrible flu" -- they were very sick and said it was the worst ever -- and, however, many of us did not catch it at all -- not even a sniffle. The same thing happened back in early 2014 -- something really severe was going around. Very healthy people were catching it. I did not, even though I was close to some of these folks. A functioning immune system is a wonderful and powerful thing. Was this contagious, or was it something environmental that was released, possibly as a test run for the COVID-19? (or both?) Did I mention that I live not far from Ft. Detrick? I think we have to ask these questions.....