The Ivy League, in 2016, moved the kickoff to the 40 yard line and the touchback to the 20. This resulted in a decrease in the concussion rate from 10.93 per 1,000 plays during kickoff before the rule change to 2.04 afterwards. This is interesting because In 2015, kickoffs accounted for 6% of all plays but 21% of concussions in the Ivy League. Other concussion rates have also fallen but no where near as much.

While it is still too early to draw definitive conclusions, it would appear that concussions can be reduced by rule changes without markedly changing the game.

The research was part of the Ivy League-Big Ten Epidemiology of Concussion Study, an ongoing initiative of the Big Ten-Ivy League Traumatic Brain Injury Research Collaboration to look at concussions across sports.

https://www.cnn.com/2018/10/02/health/kickoff-concussions-ivy-league-study/index.html