This is not what was either implied by the Vax pushers nor ever answered sufficiently by the Vax proponents.
Yes, it was. The vaccine developers have never claimed 100% efficacy. There are no vaccines that work perfectly for every person because some people have crap immune systems that simply do not develop much or any immune response to a vaccine.
The whooping cough vaccine is only about 80-85% effective and for some people it wears off in just a few years.