What do elbows have to do with fighting coronavirus?

Before the Covid-19 scare I never thought that one particular Spanish proverb would come in useful. It goes: ‘Los ojos con los codo.’ This hardly seems to make sense, ‘Eyes with the elbows’, but the great 19th-century traveller Richard Ford explains in his Gatherings from Spain that the sun’s glare on the dusty land may inflame the eyes, which must never be rubbed with the hand, only with the elbow, lest ophthalmia and blindness set in.