The immune system in children isn't primed 'particularly' for dealing with new viruses. It's that it hasn't trained itself on previous viruses and therefore at

The immune system in children isn't primed 'particularly' for dealing with new viruses. It's that it hasn't trained itself on previous viruses and therefore attacking the new ones expecting something else. Their immune system is more 'vanilla' so will create a better general response. Vaccination will not solve this, as we're already seeing, it actually enhances the problem of the immune system attacking new strains expecting the old one and missing somewhat. Look into Original Antigenic Sin