Using the MedAlerts search engine, as of July 31, 2018 there had been 3,936 serious adverse events reported to the Vaccine Adverse Events Reporting System (VAERS) in connection with chickenpox and varicella-containing vaccines since 1990. Over half of those serious chickenpox vaccine-related adverse events occurring in children six years old and under, 192 were deaths, with over 70% of the deaths occurring in children under six years of age.

And kids don't die from chickenpox, they die from a secondary infection such as pneumonia, aseptic meningitis, etc...