A pokkenbriefje is a pox letter, given by a doctor to confirm that a child has been vaccinated against the pox.
In 1823, a new law required all children to submit a pokkenbriefje before they were admitted in school. Pokkenbriefjes can sometimes be found in school records.
![pox letter](https://www.dutchgenealogy.nl/wp-content/uploads/2018/12/pokkenbriefje.jpg)
Pokkenbriefje 1877. Credits: Fledderkerspel (public domain)