I posted a statement yesterday from an industrial isopropyl manufacturer saying that 91% as a virucide is no more efficacious than is 70%.
Do you mean, 70% isoprophyl alcohol? If so, yes.
Answer
First of all, viruses are not 'alive' as such, unlike bacteria. 70% denatured alcohol will reduce the potency of most viruses if left in contact for a few seconds but will not completely 'kill' the virus. Using alcohol washes and hand rubs are beneficial in reducing virus contamination.
See http://microbiology.suite101.com/article.cfm/alcohol_based_hand_cleansers for a more complete answer.