Edward Jenner vaccinating a boy. Oil painting by E.-E. Hillemacher, 1884.

After many years of observations, Edward Jenner carried out his experiments on the effects of vaccine on human experimental subjects in 1796. On 14 May 1796 he inoculated cowpox from the arm of Sarah Nelmes into the arm of James Phipps, said to have been aged about eight years. On 12 July 1796 he inoculated Phipps with smallpox, but the smallpox did not have any effect, demonstrating the protective effects of the cowpox. This may be the episode depicted in the present painting, in which case the child receiving the inoculation would be James Phipps, while the woman holding Phipps may be identified as Sarah Nelmes