I don't get the unhealthy obsession with "unelected" in some people.
A proper -mediocracy- meritocracy (i.e. it's actual skills and qualification that counts) is preferable over any kind of popularity contest. That's not to say the WHO in particular works by this standard, I just find it very irritating if people insist on every position or institution - especially very specialised ones - being subject to elections.
That just doesn't make sense and can have horrifying consequences (see [1] for an example). There are positions (in my example: medical examiners), that simply cannot be adequately filled by laypeople and amateurs. That's not how a complex society works. It's not the middle ages anymore and most professions and many official positions require training, experience, and qualifications.
That's why I don't get the obsession with everyone needing to be "elected" (and by that I assume you mean by the general public, because WHO positions in particular are in fact awarded by elections).
[1] https://youtu.be/hnoMsftQPY8?t=277