system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 what’s Havana Syndrome? Symptoms, causes?
gpt
Short answer is we don't know. 

Basically, staff at the US embassy in Havana started experiencing health problems in the mid 2010's, and it was severe and common enough that the Government started to suspect "something was going on" and it wasn't just a bunch of random people getting randomly sick. 

The symptoms are various, but things like disorientation, hearing loss, heart problems, etc. So they are broad enough that it's not something obvious. 

There have been reports of similar symptoms in multiple nations now, so it's not just a one time event.

So, yes, it's entirely plausible that *nothing* is happening. But based on what's been made public, it's also entirely plausible that *someone* is using a new type of non-lethal weapon on embassy personnel. The theories include things like pulses of sound beyond human hearing levels, exposure to unknown chemicals or toxins, or just plain old mass hysteria.