Measles is normally the first indicator, it really springs containment pretty early, mutates a lot, really makes a problem for itself, but pertussis kills babies and when the babies start to go people really snap to attention
People have forgotten how incredibly horrible childhood mortality is which is one of if not the greatest achievement of modern science. That parents are so brainfucked as to even consider not vaccinating their children is purest madness.
I remember when this was starting to become really controversial (2021?) and other nurses were arguing "well, would you really forcibly vaccinate someone?" and: yes. absolutely yes I would