It's true that alcohol hand rubs are by no means a panacea, but they are still far and away better than soap and water. This is mostly because as you say, the key to stopping norovirus is thorough or proper washing. Which a plethora of studies have shown just doesn't take place. Today's modern alcohol gels contain a mixture of alcohols therby enhancing their spectrum of activity. The primary routes of spread of viruses tend to be aerosol (so hand hygeine won't make any difference) and ingestion of contaminated water/foodstuffs. (Which is why you only drink bottled water abroad, and then when you get the shits anyway revert to a diet of cocacola (reputable brand, contains sugar and liquid) pringles or crisps (for salt replacement) and bananas (for potassium). That said if you've got the shits real bad then sometimes it's better just ot stick to the coke. I digress) Unfortunately, viruses are easily spread by even minor contamination or food stuffs. However, one would hope that in a healthcare setting any index case (symptomatic or asymptomatic) would not be in contact with the foodstuffs of others. No making jessie in the next bed a cup of tea! Further to that, any nurse cleaning up vom or faeces has to not get herself contaminated. Complete change of clothes afterwards, than kind of thing. The standard line in HAI is that alcohol is the way forward. Unfortunately, one of the reasons it isn't as well used as it might be is that the public lack confidence in it. However, it really is the best we've got at the moment. The swiss in particular use it to good effect. I can provide refs if you want!