From personal experience, I can tell you that failure to take up the whooping cough vaccine, if the child subsequently catches the disease, will have a negative impact on their lung function for the rest of their lives.
I had whooping cough as a pre-teen in the early 1960s and was very ill for months - since which time every chest infection I get requires oral steroids and antibiotics because my lungs are so compromised as a result of the illness.
As young parents in the 1970's exH and I after much agonising decided not to allow our three youngsters to be immunised, given the conflicting advice about safety being toted at the time. Bad mistake. They contracted whooping cough one after another and it was six months before they recovered. Now as adults, they have lungs which can't cope with chest infections, either...all are also asthmatic and I bitterly regret not having the courage to have them immunised. My two youngest boys, born much later, had every vaccine going.
Yes of course one has to accept that there is a small risk with vaccines, for a very unlucky few...but believe me, the consequences of the diseases which these immunisations protect against, are life changing, in very many cases.
At the end of the day it's a personal decision of course, but trust me, you would not dither, if you had heard a young child with whooping cough struggling to breathe through the thick suffocating mucous on their lungs. It's horrifying, frightening, exhausting and very upsetting for both the child and his or her parents...and it can go on for weeks and weeks with no let up.
Thankfully, due to the immunisation programme, this can be avoided. Given my time over, I'd be first in the queue to get my children protected.