“Near the top of [its] FAQ [page], as a strategy to protect infants, the CDC says to ‘make sure everyone around the baby is up-to-date with their pertussis vaccines.’ This ‘should reduce infection in babies’, the CDC claims. Then, further down the page, the CDC states (emphasis added):
‘Many babies who get pertussis are infected by older siblings, parents or caregivers who might not know they have the disease. If pertussis is circulating in the community, there’s a chance that even a fully vaccinated person of any age can catch this very contagious disease. But if you’ve been vaccinated, your infection is usually less serious.’
A little further down yet, the CDC acknowledges that ‘we can’t rely on herd immunity to protect people from pertussis’ in part because ‘acellular pertussis vaccines may not prevent colonization (carrying the bacteria in your body without getting sick) or spread of the bacteria’.
So the greatest risk to infants is from family members who don’t know they are carriers of the disease, and vaccinated family members are more likely to be asymptomatic if they are infected.
On a related note, the CDC also admits that parents who choose not to vaccinate their children ‘are not the driving force behind the large scale outbreaks or epidemics’ in recent years.”
— Jeremy R. Hammond