For most of 2020, scientists weren't very concerned that the coronavirus would evolve. But in a few short months, variants of the virus have become a global preoccupation -- and a potential threat to vaccines.
SARS-2 was not designed as a biological weapon. Many thoughtful people dismiss this notion, and they may be right. But there is no direct evidence for theory that it was a 'natural' emergence from wild animals or an experimental mishap.
One in four air samples collected from hospital intensive care units tested positive for COVID-19 virus particles after they treated infected patients, an analysis published recently by JAMA Network Open found.