Vaccination Day

What Is Vaccination Day?

Every May 14th is also "Vaccination Day" (種痘記念日, Shutō Kinenbi) in Japan. On May 14, 1796, English physician Edward Jenner performed the world's first vaccination — inoculating 8-year-old James Phipps with cowpox (vaccinia) to protect him from the far more dangerous smallpox. Jenner's discovery of vaccination — the principle that exposure to a mild related disease could confer immunity against a more dangerous one — was one of the most consequential medical discoveries in human history, ultimately leading to the eradication of smallpox and the development of vaccines for dozens of diseases.

Edward Jenner and the Discovery of Vaccination

Edward Jenner (1749–1823) made his breakthrough observation that milkmaids who contracted cowpox appeared to be immune to the far more deadly smallpox. His 1796 experiment — deliberately infecting young Phipps with cowpox and then exposing him to smallpox, finding him immune — was both bold and successful. Jenner published his findings in 1798, and vaccination spread rapidly through Europe and beyond. Jenner's discovery preceded any understanding of the germ theory of disease or the immune system — he discovered a working solution before fully understanding why it worked.

Vaccination in Japan

Smallpox vaccination reached Japan in 1849, when Dutch physician and Japan scholar Jan Karel van den Broeck brought vaccine material to Nagasaki. The vaccination concept spread through Japan's medical community during the late Edo and Meiji periods, contributing to Japan's public health modernization. Japan's current vaccination program — coordinating routine childhood immunizations, annual influenza vaccines, and outbreak responses — is one of the world's most comprehensive and achieves high vaccination coverage rates.

Vaccination and Modern Public Health

Vaccination is the single most cost-effective public health intervention ever developed — responsible for eliminating smallpox (1980), dramatically reducing polio, measles, and diphtheria, and preventing millions of deaths annually. Japan's vaccination history includes both achievements (high routine immunization coverage) and controversies (vaccine injury compensation disputes in the 1990s that temporarily reduced confidence in certain vaccines).

Fun Facts

• Smallpox eradication: The WHO declared smallpox eradicated on May 8, 1980 — the first and only human disease to be completely eliminated through vaccination. Japan's routine smallpox vaccination was discontinued in 1976 as eradication neared completion.
• COVID-19 vaccination: Japan's COVID-19 vaccination campaign — beginning in February 2021 — eventually achieved one of the world's highest vaccination rates, with over 80% of the population receiving full vaccination, contributing to Japan's relatively favorable COVID-19 outcomes.