Dr. Meryl Nass MD Testimony Before the Education Committee About Vaccines – AHRP
Pertussis is a problem, because the vaccine works poorly.
66% of Maine cases were fully vaccinated, 83% partially.
The TDaP pertussis vaccine is estimated 67% effective the first year after inoculation, but only 9% effective 4 years later. 
Almost all of us are susceptible to pertussis despite vaccination. I have had pertussis twice. I am fully vaccinated.
Given the failure rate of the pertussis vaccine, no herd immunity is possible. The bacteria regularly circulate in the community, as they would even with a 100% vaccination rate.
Pertussis is not a major problem for the immunocompromised, who are in fact regularly exposed.
Similarly, Varicella (the virus that causes chickenpox and shingles) cannot be eradicated even with a 100% vaccination rate.
A full 70% of Maine children who got chickenpox in 2017 had been vaccinated.
Adults with shingles spread the virus; a disease-free environment cannot be attained.
Fortunately, children do not die from varicella, even highly immunocompromised children, for whom several treatments are available. There is approximately one child death per year, in the entire US, from Varicella.