Before vaccines are made mandatory for going to school I believe that several years should pass to determine if there are any effects on pregnancies or babies born to vaccinated women.  I am not familiar with specific cases of vaccines causing birth defects or other issues with babies, but this is a new type of vaccine and the long term health of society should be considered.  Have a percentage of the population not vaccinated is a risk-mitigation against any fertility issues or children being born after this vaccination process that are not discovered until a later time.  If all children are vaccinated and then there ended up being some kind of issue related to fertility or birth defects/etc. then we would have made a major mistake by jumping too quickly to implement a vaccine mandate for all school children.

Note: I am vaccinated.  I am thinking with a level head about the future of society and managing ALL the risks, not just the short term ones.