Leicester Square, 12th March, 1799.
Sir,—I hope you will pardon me for taking the liberty to inform you (by way of additional evidence to the testimonies I have published on the subject of the Cowpox) that upwards of 160 patients, from two weeks to forty years of age, principally infants, have been inoculated since the 20th January last by Dr. Woodville and myself, separately....
Not one mortal case has occurred.
Not one of the patients has been dangerously ill....
None of the patients, namely above 60, inoculated with the Smallpox, subsequently to the Vaccine Disease, took the infection....
In many of the cases eruptions of the body appeared, some of which could not be distinguished from the Smallpox.
I have sent the matter of Cowpox pustules on the thread enclosed, in order, if you approve of the inquiry, to inoculate with it; and I entreat you to favour me with the result of your trials: but I must trouble you to apply the test of inoculating with variolous matter subsequently to the vaccine disorder.
George Pearson, M.D., F.R.S.
P.S.—I am happy to be able to state that at Berkeley, Dr. Jenner has continued his trials of inoculation with vaccine matter sent from London with good success.