I think the Chinese are referring to the fact that if they cut the supply of masks, gloves, syringes, antibiotics, and so on to us - it would place our doctors in an untenable situation and the virus would likely spread exponentially. We buy a LOT of material from them and some things aren’t made in sufficient quantities anywhere else, anymore.
If our population is significantly harmed via a biohazard incident from China, we would nuke them. This is a given.