CNN is reporting:

Conducted by scientists at the Vaccine Study Center, the research looked at nearly half a million children born between 1999 and 2016, and found that most whooping cough cases — 82% — occurred in children who were fully vaccinated or over-vaccinated.

“The bigger picture is that we’ve had several outbreaks of pertussis here in California over the past 9 years,” said Dr. Nicola Klein, a co-author of the study and director of the Kaiser Permanente Vaccine Study Center. She emphasized that the vaccine generally works, but noted that “most of the children who had pertussis in our outbreaks were fully vaccinated.”