The study you cite doesn't seem to say what you want it to say. > Controlling for differences across studies, secondary attack rates were higher in households

The study you cite doesn't seem to say what you want it to say. > Controlling for differences across studies, secondary attack rates were higher in households from symptomatic index cases than asymptomatic index cases, to adult contacts than to child contacts, to spouses than to other family contacts, and in households with 1 contact than households with 3 or more contacts. It acknowledges asymptomatic spread.