Facts for the most part unobserved or not duly noticed respecting Variolous Contagion. London: 1808.
1808.—It should be remembered that the constitution cannot, by previous infection, be rendered totally insusceptible of the Variolous Poison. Neither the casual, nor the inoculated Small Pox, whether it produce the disease in a mild or violent way, can perfectly extinguish the susceptibility.—P. [338].
Letter to William Dillwyn on the Effects of Vaccination in Preserving from the Small Pox. Philadelphia: 1818.
1818.—My confidence in the efficacy of Vaccination to guard the constitution from Small Pox is not in the least diminished. That exceptions to the rule have appeared, and that they will appear, I am ready to admit. They have happened after Small Pox Inoculation; and by the same rule, as the two diseases are so similar, they will also happen after Vaccine Inoculation.—P. [344].
Last Testimony.
1823.—My opinion of Vaccination is precisely as it was when I first promulgated the discovery. It is not in the least strengthened by any event that has happened, for it could gain no strength; it is not in the least weakened; for if the failures you speak of had not happened, the truth of my assertions respecting those coincidences which occasioned them would not have been made out.—P. [354].
The whole of Jenner’s claims re-asserted for Smallpox Cowpox by Mr. John Simon, after Inoculation with which—
1857.—“Neither renewed vaccination, nor inoculation with Smallpox, nor the closest contact and cohabitation with smallpox patients, will occasion him to betray any remnant of susceptibility to infection.”—Papers relating to the History and Practice of Vaccination. London: 1857.—P. [513].
Jenner’s Successive Poxes