The fact that children must be vaccinated is justified in the same way as for adults, to protect themselves and others. This is even though children have an extremely low risk of severe Covid, and that children are not an important source of infection. It is also often justified by the fact that it is needed for society to be able to open and for restrictions to be removed.
It is unethical to put children and young people at risk to protect adults. How can it be right to exploit children’s willingness to help in this way, when we know that the vaccines do not work, that they neither protect against the spread nor against infection? The reason why the vaccine protects against serious illness is not relevant for fundamentally healthy children.