Although the demonstration in 1796 by Edward Jenner that vaccinia virus could protect against smallpox was epochal, he was following the path opened by the ancients who had used the smallpox virus itself in the practice of variolation. The work of Louis Pasteur on chicken cholera opened the way to vaccine development in the laboratory. In April 1880, Pasteur reported to the French Academy of Science that “…chicken cholera is produced by a microscopic parasite [now known as Pasteurella multocida], that there exists an attenuated virus [Pasteur was using “virus” in the ancient sense of the word] of that disease, and that one or more inoculations of this attenuated virus can preserve the animals from the mortal effects of a later inoculation … let me be permitted to use the word ‘vaccinate’ to express the act of inoculating a chicken with the attenuated virus” [1]. Thus, the word “vaccinate” was extended beyond vaccinia and came to have its modern meaning. Today, epidemic infectious diseases of children for which there are vaccines have virtually disappeared from industrialized countries such as the United States. These are remarkable successes, which together with clean water and antibiotics have profoundly affected human society [2]. In addition, a new field of microbiology and immunology has evolved, called “vaccinology,” that comprises not only vaccine development but also the use of vaccines and their effects on public health [3]. Here, I will briefly cover some aspects of the past, discuss 5 current issues in vaccinology, and then turn to the future.