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.
[1] 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.
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.
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.
Pastor Schmidt and his superior, provost Cay Wilhelm von Ahlefeldt, negotiated a modest pension and accommodation with the citizens of Stakendorf.