I Googled the shelf life of Aqua Mira: 4 years.

From the same report on the EPA's website, it also states: "Chlorine dioxide has been shown to be an effective viricide..."

Sorry, I just always think of cysts as being the more difficult nasty to get rid of; therefore, since it does a decent job on cysts, I presumed it would be even more effective inactivating viruses. I'm no Microbiologist by any means, so if I'm wrong here, then chime in!

Eric
P.S. I hope I don't get in trouble for reproducing all this information! <img src="/forums/images/graemlins/shocked.gif" alt="" />