Partial answer- because Corona is not new and some work has already began a while ago. For example this [1] Israeli company > MIGAL initiated its Corona-vacci

Partial answer- because Corona is not new and some work has already began a while ago. For example this [1] Israeli company > MIGAL initiated its Corona-vaccine development program four years ago with $4 million funding by the Israeli Ministry of Agriculture. Although it was originally for chickens... [1] http://www.migal.org.il/en/node/7010 http://www.migal.org.il/en/node/7010