It's worth noting that this document does not make any claim that it cannot spread prior to symptoms. It says this:
" - People are thought to be most contagious when they are most symptomatic (the sickest).
- Some spread might be possible before people show symptoms; there have been reports of this occurring with this new coronavirus, but this is not thought to be the main way the virus spreads."
https://www.cdc.gov/coronavirus/2019-ncov/about/transmission...
It's worth noting that this document does not make any claim that it cannot spread prior to symptoms. It says this:
" - People are thought to be most contagious when they are most symptomatic (the sickest). - Some spread might be possible before people show symptoms; there have been reports of this occurring with this new coronavirus, but this is not thought to be the main way the virus spreads."