Good question. That would be a reference to Google's Neural Matching Algorithm. It was officially announced by Danny Sullivan in a series of tweets. It's real. All SEOs should acquaint themselves with Neural Matching.
Imo, it's caused Google to jump ahead of Bing in terms of ability to return useful content for ambiguous search phrases. I wrote an in depth article about that algorithm, including screenshots of announcements and links to research here: https://www.searchenginejournal.com/google-neural-matching/271125/
And here is the link to Danny Sullivan's series of tweets discussing this important change:
Shaddows is correct in stating that the reason why some "medical" related sites got hit was because of a problem with their approach
to the topics, which rendered them less relevant. This is my observation as well based on websites that I have audited.
And that is what I meant when I posted above that those who named the update Medic mistook the symptoms (medical sites got hit
) for the illness (reclassified relevance to user search query
It was not about niche or topic. It was largely about understanding user queries. The Most Important Algo Change Since Penguin?
The AI component (Neural Matching) is, in my opinion
, the most important algorithm change since Penguin. And this is the change that nobody's really discussing. But if you read my article about the Neural Matching algorithm (as well as the companion piece about the algo I linked to above) you'll see how incredibly complex this algorithm actually is.
It is very difficult to speak of it in a simplified form so that it's easier to understand but I gave it my best shot. Danny Sullivan gives a good breakdown by introducing the concept of super synonyms, which helps.