I looked into this recently and found that some are and some aren’t. For the ones that are, I saw a few places that said 60% was the minimum alcohol concentration necessary to be effective.
More info from here:
…but it is possible that we have a somewhat false sense of security if we assume that alcohol-based cleansers will rid our hands of viruses.
It is true that some viruses are readily inactivated by alcohol; however, some are not. Viruses consist of nucleic acid (either RNA or DNA) surrounded by a capsid (protein shell). Some viruses have an additional external layer or wrapping known as an envelope. The envelope is created from a piece of phospholipid membrane that comes from the infected host cell during the “budding” process when viral particles leave the infected cell. Enveloped viruses are referred to as lipophilic viruses, because of their lipid envelope, while nonenveloped viruses are referred to as non-lipophilic viruses.
Generally, enveloped (lipophilic) viruses are susceptible to alcohol: Herpes simplex virus (HSV), human immunodeficiency virus (HIV), influenza virus (Flu), respiratory syncytial virus (RSV), vaccinia virus, Hepatitis B and C viruses are considered susceptible to alcohols.
However, certain nonenveloped (nonlipophilic) viruses such as hepatitis A and enteroviruses, which are both responsible for viral gastrointestinal infections. Depending on the alcohol concentration of the hand-cleanser and time of exposure to the alcohol, hepatitis A and other nonlipophilic viruses may not be eliminated.