I find the herd immunity arguement difficult. It doesn't make sense to me.

As a PP said - I think vaxing is so misunderstood that people get a false sense of security, and stop taken the proper precautions to prevent spread of illness and disease (whether it be the common cold or a more serious 'preventable' disease).

In my understanding, vaccinating an individual at best produces a mild illness, but they can still pass it on. And if you are only mildly sick, you still go to school, get sent to childcare, or go to work, exposing others, who may get a mild case, pass it onto others, until someone smooches the vunerable newborn. The newborn gets sick, but everyone else feels fine, so they treat it as a cold...until the point where the child is so sick, that the illness is now severe and needs hospitalisation. I wish no disrespect or assumptions about the case in the OP (which I am not familiar with), I am talking generally. There are many ways to prevent the spread of disease, understanding how germs are spread is for more empowering than solely vaxing. Each family must decide what suits their situation, and weigh up for themselves their likely hood of exposure. BUt it is everyone's responsibility to be hygienic and to do the right thing to prevent the spread of disease - wash hands, put tissues in the bin, wash hands, cover mouth, wash hands, and use common sense and stay away from families with newborns if you or those close to you have been sick.
Yeah that! Well said.