Steps to check high and dangerous tackles led to a significant decrease in concussion-related injuries at last year's World Cup says World Rugby.
The tournament in Japan was the first World Cup to introduce World Rugby's "high tackle framework" - the step-process of decisions referees must consider when analysing a potentially dangerous tackle - which is designed to reduce the risk of head injuries by "changing player behaviour from high-risk upright to lower risk bent-at-the-waist tackles".
In a statement World Rugby said there was a 28% reduction in the overall incidence of concussion and a 37% drop in tackle concussions at the tournament compared with the average figures from elite events two years ago.
"These hugely encouraging outcomes endorse our unwavering evidence-based commitment to injury prevention, particularly our continued efforts to protect players from concussive events on the rugby field," World Rugby chairman Bill Beaumont said.
"The significant reduction in concussion incidence provides compelling evidence of what can be achieved when competition owners, match officials, disciplinary officers, players and coaches fully buy in to the High Tackle Sanction Framework.
"Failure to do so can have significant player welfare and performance consequences."
World Rugby said the reduced numbers were linked to tough deterrents and an awareness programme held before the event.
Yellow cards shown by referees at Japan 2019 increased by 74% and red cards by 138% against the 2018 average.
World Rugby said that there was also an overall decrease in injury incidence from 90 per 1,000 player hours at the 2015 World Cup to 83 in Japan.
The average number of injury replacements per game fell from 2.08 in 2015 to 1.13 in 2019.
World Rugby chief medical officer Eanna Falvey said the body would continue to adopt a collaborative and evidence-based approach to understand where it could further reduce the risk of concussion in the sport.
World Rugby said it was also evaluating a "High Tackle Technique Warning" as part of new law trials. It said the aim was to motivate changes in player and coaching behaviour by issuing off-field sanctions for poor tackle technique and rewarding positive behaviour.