For the Northern Hemisphere this flu season they recommend strains like A/Brisbane/02/2018(H1N1), A/Kansas/14/2017(H3N2), B/Colorado/06/2017, and B/Phuket/3073/2013.
Those are virus strain identifier names, not disease common names. IN that case the disease is called influenza.
The WHO advice applies to the common usage:
As these best practices only apply to disease names for common usage, they also do not affect the work of existing international authoritative bodies responsible for scientific taxonomy and nomenclature of microorganisms.
https://www.who.int/topics/infectious_diseases/naming-new-di...
Of course older diseases would not likely have their names changed.