YSK What to do if someone’s choking: Evidence says begin with back blows

Why YSK: > Despite choking being an emergency, until recently there has been limited high-quality evidence to guide bystanders on the most eff…

Interesting because all of my first aid instructions say not to slap people on the back. Why should I believe this over instructors and doctors?
You can read the wikipedia about the abdominal thrusts that another comment linked. There’s a line in there about heimlich not being ‘scientific’ in his pushing of the abdominal thrusts and denigration of back blows.