Concussions were down 28 percent at the 2019 Rugby World Cup in Japan compared with the 2018 elite competition average, World Rugby announced on Wednesday.
The tournament, the first World Cup to feature the high tackle sanction framework, also saw a 37 percent reduction in tackle concussion incidence.
The framework, which provides a step-by-step method for grading and sanctioning a high tackle, was designed to help reduce concussion risk by changing player behaviour from high-risk upright to lower-risk bent-at-the-waist tackles.
World Rugby said the Japan 2019 outcomes "indicate promising early signs that the framework approach is effective".
Yellow card sanctions at the tournament increased by 74 percent and red cards by 138 percent compared with the 2018 elite competition average, with the governing body saying the "tough deterrent was a direct contributing factor" to the reduction in concussions.
World Rugby also said Japan 2019 saw an overall reduction in injuries from 90 injuries per 1,000 player hours in 2015 to 83 injuries per 1,000 player hours.
"These hugely encouraging outcomes of this study endorse our unwavering evidence-based commitment to injury prevention, particularly our continued efforts to protect players from concussive events on the rugby field wherever possible," said World Rugby chairman Bill Beaumont.
"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."