The document discusses vaccination against shingles and the varicella zoster virus. It provides background on shingles, including that it is caused by reactivation of the same virus that causes chickenpox. It notes statistics on shingles incidence and effectiveness of the Zostavax vaccine in reducing risk. It also discusses natural immune system suppression of the virus and factors that can increase risk of shingles reactivation like aging, stress, and immunosuppression.