Home > Dermatology > How Contagious is Chickenpox Get the Flash Player to see this player. Rate: (Click the stars to rate) Published on Mar 29, 2009 by DBehroozan, Views: 4596 How contagious is chickenpox. Chickenpox is very contagious. IF you have never had chickenpox, you should avoid someone who has chickenpox, or shingles, which is a reactivation of the chickenpox virus. Dr. Daniel Behroozan.