New Kaiser Permanente research published in the journal Pediatrics finds children who were up to date on their pertussis vaccine schedule were far less likely to develop the disease than unvaccinated children. The research also finds that most pertussis cases were in fully vaccinated children and that the risk of illness increased with the time elapsed since vaccination. These findings suggest that waning effectiveness between doses was a significant contributor to recent outbreaks.

Photo credit: CDC/ Amanda Mills

The study, “Acellular Pertussis Vaccine Effectiveness Over Time,” was published on June 10, 2019.

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Pertussis, widely known as whooping cough, is a highly contagious and potentially life-threatening respiratory infection caused by the bacterium Bordetella pertussis. To help prevent it, the Centers for Disease Control and Prevention recommends 5 doses of DTaP vaccine — a combination vaccine that protects against pertussis, diphtheria, and tetanus — between the ages of 2 months and 6 years.

“Most DTaP research has explored either vaccination status or waning effectiveness, but we looked at both at once,” said Ousseny Zerbo, PhD, lead author of the new study and a staff scientist with the Vaccine Study Center at Kaiser Permanente Northern California’s Division of Research.

Dr. Zerbo and his colleagues retrospectively analyzed the electronic health records of 469,982 children under the age of 11 who were members of Kaiser Permanente in Northern California. Focusing on data from January 2006 through June 2017, they performed a series of statistical analyses to determine risk of pertussis according to vaccination status and the time since a child’s last dose.

Read more at Kaiser Permanente