It is the sentry who shouts at the microbes: “They shall not pass!”

Le Monde illustré editor Alfred-Jousselin reporting on remedies for the Spanish flu in November 1918. Photo caption: Pharmacists are having a hard time satisfying an excess of customers demanding potions and pills. Do not trifle with Goménol: it is the sentry who shouts at the microbes: “They shall not pass!”
(Goménol was the trademark for a concoction of Melaleuca quinquenervia from New Caledonia.)
From the main text: Alfred-Jousselin reports on the British reaction to influenza: “they told themselves that living as much as possible in the open air was the best way to avoid contagion; they went out a great deal and remained outside their home throughout the day: but, calamity of calamities, here is what an investigation done very scrupulously has revealed, that the trades most cruelly affected by influenza were precisely those whose practitioners were constantly in the open air: drivers of cars, of buses, road workers, policemen, letter carriers, firefighters, etc. So we wondered with concern if it was not the air that was developing the flu, and making it more dangerous. A new party was formed: that of the stay-at-home types, who no longer risk the tip of their noses outside: we will soon know the results that the cloistered life will have given.
To avoid a confined existence, or to heal if one is affected by malady, is there some sovereign panacea, some saving remedy? Well, no.”
(Gallica)