The 2019 revision notably includes devastating illnesses like "job burn-out," which is "a syndrome conceptualized as resulting from chronic workplace stress that has not been successfully managed." Which, in our experience, pretty much describes every job we've ever held. And while the WHO doesn't explicitly say it, we assume that they see the job-creating Donald Trump as the Typhoid Mary of stress-inducing employment.
(Worth noting is the fact that there is still no vaccination for burn-out, although researchers at the Clan MacGregor distillery say "shots can help," which we can personally confirm.)
The WHO also updated their definition of "compulsive sexual disorder," a very serious condition best known for afflicting a former president who shall remain nameless, but whose wife's name is Hillary.
Happily, not all of the handbook's revisions were adding new medical conditions - some old ones have been reconsidered by the great medical minds in Geneva, Switzerland and it turns out that they weren't illnesses at all! As a case in point, transgenderism is no longer described as a "mental disorder," but simply a "natural variation of human experience."
This comes as great news to transgender folks, because many governments previously insisted on a medical "gender disorder" diagnosis before changing people's names and gender markers on official documents. But with the banishment of "gender disorder," anyone is now free to demand legal paperwork substantiating whatever name and gender currently tickles their fancy. (medical note: "fancy" is the official term for transgender genitalia).
The WHO handbook has literally hundreds of other interesting medical updates but unfortunately we're not able to comment on them at present. It's time for us to take our shot (or two) to avoid job burn-out.