In vaccinating against small-pox the important question which arises is: "Did the vaccination take?" Now that typhoid vaccination is becoming more and more popular in civil life it is just as important for the physician to know whether his subjects really become immune to typhoid or not, for if his vaccine has been kept on the druggist's shelf for a couple of years or a faulty thermostat in the manufacturer's laboratory has caused it to be overheated, he may vaccinate with it by the bucketful without results. The individual may be happy who thinks he is protected from typhoid, but is not, and who drinks his polluted water without a tremor, but his position is not one to be envied.
In vaccinating a large body of people, as a whole army, where the vaccine has already proved good and the conditions always remain the same, it would be troublesome and
MAVERICK A. TYPHOID VACCINATION AND THE WIDAL REACTIONWITH REPORT OF A CASE WHICH FAILED TO SHOW A POSITIVE WIDAL AFTER THREE SUCCESSIVE VACCINATIONS. JAMA. 1912;LVIII(22):1672–1675. doi:10.1001/jama.1912.04260060021006