I happened to be at the epicenter of the outbreak of coronavirus in Italy and I knew I should make sure my immune system is perfect before doing anything else. I gave the e-book a shot because it was just 7e without expecting much, but to be honest, I learned and applied more from the book which actually helped me feel better even if wasn't sick or infected (hopefully). So, yeah, I believe it truly worth it. Applicable information not only for the virus, but your immune system in general.