When I was a kid from the wrong side of the tracks, wiping your nose on your clothes was a marker of social class. Lots of us girls were very keen on our hankies, though. I used to embroider initials on them and crochet lace around their edges.
Now it's hankies that should make people go ewww! and the upper sleeve should be respectable for catching coughs and sneezes.
Before they became controversial as germ-catchers, the European handkerchief had an interesting history - and rather a long association with class. Erasmus apparently said the cap or the sleeve "might be alright for pastry-cooks," but hands were a bit better and handkerchiefs were what social betters should use. Marie Antoinette has been credited with insisting - ultimately supported by royal edict - that hankies be square. Perhaps that one's an apocryphal tale. Wikipedia says the material hankies are made of still "can be symbolic of the socio-economic class of the user."
Back in the Spanish flu era early last century, covering your mouth with a handkerchief when you coughed or sneezed was recommended in the US. And face masks made of gauze were used in sickrooms and hospitals.
Now, according to the CDC, tissues are the first line - to be tossed in the waste afterwards, with the upper sleeve or crook of the elbow as back-up if you don't have a tissue handy. In 2009, this picked up the nickname, "the Dracula Sneeze," after the full Dracula pose.
The CDC also recommends washing your hands with soap and warm water for 20 seconds often, or using an alcohol-based hand rub.
Has all this taken off? Not so much. An observational study in New Zealand during a flu epidemic found that less than 4% of people used a hanky or tissue and less than 2% used their elbow or arm to cover their coughing and sneezing. They were more likely to cover up when they were close to other people.
Some people don't shake hands, kiss others or share glasses when they've got a cold, but when the flu's going around, you don't see all that big a change in social life.
There certainly seem to be some people using hand-sanitizers in some countries, but that doesn't seem to be all that common either. Not many use those dispensers provided in institutions.
That people don't really do these things is one of the barriers to them working, but not the only one. We can spray those droplets up to 6 feet away, and they last on surfaces for 2 to 8 hours. The virus gets into our respiratory system either directly by droplets reaching our eyes, nose or mouth, or from our hands when we touch our faces. There are just so many ways for the flu virus to spread.
Logically, if there's no one around, since it's hard to keep our hands away from our faces, sneezing or coughing directly into your hands would be worse than not covering up - hence the recent advice.
A systematic review by Tom Jefferson and colleagues with an updated search in 2010 found the evidence about what works and doesn't work has grown a little. But given how important this topic is, it's rather shocking we don't have more rigorous trials testing all these theories.
So what did Jefferson conclude? The cough/sneeze hygiene and frequent hand-washing interventions seem to have the most effect in children - likely because their hygiene is the worst and their close social contact is greater than anyone else's. Frequent hand-washing or hand sanitizer use do work, but antiseptics aren't necessarily better. What "often"or "frequent" means isn't clear, though.
Ordinary surgical masks can help - full-on gas masks aren't necessarily better, although eye goggles might help those caring for someone with a dangerous respiratory infection.
Doing more things to reduce transmission rather than fewer is better. Keeping your distance from people who are infected does seem worthwhile, although the studies haven't been very good.
There's more about protecting yourself from respiratory viruses in this fact sheet.
Want to know more about sneezing? Here's a great post by SciCurious.
The public health poster is from around 1925, in Wikimedia Commons.
* The thoughts Hilda Bastian expresses here at Absolutely Maybe are personal, and do not necessarily reflect the views of the National Institutes of Health or the U.S. Department of Health and Human Services.