Package: release-notesSection 2.2.5 in the jessie release notes states that MySQL 5.5 support ends in December 2017, but extended support lasts until December 2018 [1], and that includes bug fixes [2]. So patches should be coming until at least December 2018.
Regards, Norvald H. Ryeng[1] http://www.oracle.com/us/support/library/lifetime-support-technology-069183.pdf
[2] https://www.mysql.com/support/