"If the Chinese have waged economic war using a biological agent from a commonly occurring family of viruses, then they have either managed to immunise their own people so they don't get affected, or they were willing to sacrifice a small percentage of their population to win the war. By using such a common virus, they have plausible deniability and can't be seen as using military means to achieve their goals. "
I believe that China would have no hesitation in sacrificing a small percentage of their population to achieve their own goals. It would be cheaper than waging a normal military war in terms of lives lost