The pertussis vaccine works really well, according to a new study comparing kids in Alaska who had gotten three or more doses of the vaccine with children who were unvaccinated, or undervaccinated.
The diphtheria, tetanus, and acellular pertussis (DTaP) vaccine is a routine childhood combination immunization that’s given in a five-dose series, starting at two months of age, with the last dose between the ages of four and six years.
A paper yesterday in the Morbidity and Mortality Weekly Report (MMWR) found that, compared with fully vaccinated children, those who were unvaccinated had approximately 26 times the odds of having a confirmed case of pertussis, sometimes called whooping cough, which is caused by a bacterial infection.
The paper focused on kids from the ages of six months through six years during Alaska’s 2024 pertussis outbreak, which saw the highest case rate on record in the state. Researchers from the Centers for Disease Control and Prevention (CDC) and Alaska Department of Health used records from VacTrAK, the database that tracks all vaccinations administered in the state. As a control, the study included kids who were treated for an acute cough, but either tested negative for pertussis or did not receive testing.
The overall adjusted vaccine effectiveness (VE) rate against pertussis among children who had received three or more DTaP doses was 96.2%. Also, VE was 85.3% among kids who were partially vaccinated, meaning they had received just one or two DTaP shots.
Pertussis can lead to fractured ribs, brain damage, even death
These real-world findings support childhood vaccination recommendations, said the authors, who pointed to previous research showing that unvaccinated kids are more likely than those who are vaccinated to experience severe illness or require hospitalization.
Pertussis can lead to devastating outcomes among young children, including brain damage and deaths: A provisional CDC report found that 16 people died from this bacterial infection in 2025, including 10 infants. Other complications include pneumonia, vomiting after a coughing fit, or coughing that is so frequent and violent that a child fractures their rib.
The DTaP vaccination rate among kindergartners in the United States has fallen in recent years. CDC data show it dropped to 92.0% for the 2025-26 school year; in 2017-18, it was 95.2%.