Elderberry has been used as a colds & flu remedy or preventative throughout history, and has gained a lot more attention recently for its potential benefits in protection from Covid-19, as the mechanisms of action of its most active components (eg. caffeic acid) may target docking and entry of the virus into cells. Whilst the elder flower (fläder) is more popular than the berry in Sweden, being used traditionally to make a cordial/squash, its easy enough to make your own Elderberry syrup (from the berries).
Completely unaware that 3 months later the world would be in pandemic status with a virus for which elderberry seems to have been 'made', last autumn I went out collecting bunches of elderberries in my local area and tried out making my own syrup. The berries can be stored in the freezer and you can make a batch of syrup when you feel its cold and flu season.
I first thought I could avoid the addition of sugar by making a berry compot, but that was a complete failure, and I accepted that making a filtered drink is the only way to go. Note that it is important to do the cooking step properly to allow the cyanide in the seeds to escape. Elderberries cannot be eaten raw. I searched for the best recipe, and this is the one that rang home with me. It has ginger, cinnamon and cloves and used honey instead of sugar. Of course if you want a vegan option you could use sugar or agave/maple syrup instead.