Bulgaria was one of the partners of the Central Powers along with Germany, Turkey and Austria-Hungary. This is a mid war Vivat which is actually quite late (18 January 1916) as most were issued in 1914-1915.
It celebrates the allies of Germany and Bulgaria. The two leaders are conversing together. Below them we see crossed swords and the furled flags of both nations. At the very bottom of the Vivat we see that it was issued for the benefit off the German Red Cross. Finally in the top left corner we see a mark where a price sticker was one attached.