The whole sentence could use some more punctuation marks, like so:
A large number of young people across different countries are affected, with considerable impact on health care systems and society as a whole. Since spread via social media is no longer restricted to specific locations such as local communities or school environments, spread via social media is no longer restricted to specific locations such as schools or towns.
A large number of young people across different countries are affected, with considerable impact on health care systems and society as a whole. Since spread via social media is no longer restricted to specific locations such as local communities or school environments, spread via social media is no longer restricted to specific locations such as schools or towns.