Where did you get that idea? You can take it as a preventative (roughly ½ dose + daily zinc, IIRC) just like when taking HCQ in mosquito ridden countries to prevent malaria. The malaria and CV can't replicate with HCQ/zinc in your system, never gains a foot hold. The only thing holding normal Americans back from a preventative script are US drug regulations. HCQ is sold OTC in many malaria ridden countries, the people there take it like non-prescription allergy medication during malaria season.