annually in the u s yes as the cdc source says i believe the free full text is available but since you're skeptical i'll quote during varicella was the underlying cause of death in an average of children aged less than years each year cdc unpublished data during up to children were hospitalized each year for varicella or its complications cdc unpublished data ninety percent of the children who died did not have high risk conditions for severe varicella if someone ends up on a ventilator as a result of varicella pneumonia and then winds up succumbing to a staphylococcal superinfection then it is reasonable to ascribe that death to varicella and to call it vaccine preventable as the cdc does '''''' talk