Pertussis Burden Lower in Young Infants Following Advice to Vaccinate in All Pregnancies

By Megan Brooks

December 05, 2019

NEW YORK (Reuters Health) - Giving pregnant women the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine appears to benefit infants younger than 2 months old who are too young to be vaccinated, a new analysis confirms.

"We found that rates of pertussis (whooping cough) hospitalizations among young infants decreased after providers started recommending Tdap vaccination during every pregnancy," Dr. Sheree Boulet of Emory University School of Medicine, in Atlanta, told Reuters Health by email. "These results suggest that getting the Tdap vaccine during pregnancy can prevent serious complications among infants too young to be vaccinated."

To help reduce illness and death from pertussis among young infants, in 2012, the Advisory Committee on Immunization Practices (ACIP) recommended Tdap administration in every pregnant woman, regardless of prior receipt.

Pertussis cases among infants younger than 1 year decreased after 2012 in the U.S. However, less is known about trends in young infants. To investigate, Dr. Boulet and colleagues analyzed trends in pertussis hospitalizations among infants younger than 2 months before and after the 2012 ACIP recommendation.

Using data from Truven Health Analytics Marketscan Commercial databases, they identified about 1.9 million infants (52% male) born between 2009 and 2017, with two months of follow-up. The outcome of interest was pertussis hospitalization occurring between birth and 2 months of age.

The rate of pertussis hospitalizations was 8.4 per 100,000 infants for the period 2009 to 2012, and fell to 3.3 per 100,000 infants between 2013 and 2017. After adjusting for time, there was a 48% decrease in the rate of pertussis hospitalization in the period after the 2012 ACIP recommendation, a statistically significant change, the authors report in JAMA, online December 3.

They note that the data they used came from a privately insured population and the findings may not be representative of all infants. Also, the use of ICD codes to identify pertussis hospitalizations may have resulted in misclassification.

Despite these limitations, the authors say, "The results of this large national study indicate a decline in pertussis hospitalization rates among young infants after the 2012 recommendation change. These findings underscore the public health importance of maternal Tdap vaccination in reducing pertussis burden among young infants. Clinicians should continue to promote maternal Tdap vaccination and find ways to overcome barriers to vaccination during pregnancy."

"Only 55% of pregnant women in the U.S. get the Tdap vaccine. Women may not know that they need to receive the Tdap vaccine during each pregnancy to protect their baby against pertussis (whooping cough), which is why it is important that providers talk with pregnant women about Tdap vaccination," Dr. Boulet told Reuters Health.

The study had no commercial funding and the authors have no relevant disclosures.


JAMA 2019.