Plett was born on 29 December 1766 in
Klein Rheide,
Duchy of Schleswig. In 1790, Plett was employed as a home tutor in
Schönweide where he learnt from milkmaids about
cowpox preventing humans from being infected with smallpox. In 1791, he moved to the
Meierhof at Hasselburg in Gut Wittenberg/East-Holstein where he vaccinated its owner Martini's three children with cowpox lymph which protected them against smallpox. Only five years later,
Edward Jenner discovered this very method which made him world-famous. In 1790 and again in 1791/92, Plett reported his success to the medical faculty of the
University of Kiel, but they favoured the older method of
variolation so they did not act on the reports. In 1802 after Jenner's method had reached the area, Plett was interviewed by
Friedrich Adolf von Heinze on behalf of
Christoph Heinrich Pfaff from the Medical Faculty of the University of Kiel. His report was published by Pfaff and Heinze and later forwarded to the German Office of the government in
Copenhagen. From 1793 on, Plett attended the
teachers' seminar headed by Heinrich Müller in
Kiel. He was encouraged by his principal pastor
Johann Georg Schmidt who considered him "one of Müller's most promising seminar attendees" and engaged him as a teacher in
Laboe in 1796 in
Stakendorf in 1808.
Franz Hermann Hegewisch, who became a professor of the University of Kiel in 1809, discovered Plett's reports about his success with cowpox vaccination and the university's ignorance. He recommended publishing an article about Plett's discoveries to the editor of the
Neue Schleswig-Holsteinische Provinzialberichte (New provincial reports of Schleswig-Holstein),
Georg Peter Petersen. In 1815, Petersen published the previous year's interview with Plett, so he confirmed Heinze's report of 1802. In 1820, Plett was forced to retire from teaching due to his
alcoholism. Pastor Schmidt and his superior, provost
Cay Wilhelm von Ahlefeldt, negotiated a modest pension and accommodation with the citizens of Stakendorf. Three years later, Plett died at the age of 56. == Honours==