BACKGROUND AND PURPOSE:

• In 2012 ACIP recommended that all pregnant women receive the Tdap vaccine, even if previously vaccinated
• Boulet et al. (JAMA, 2019) investigated trends in pertussis hospitalizations in the US among infants younger than 2 months before and after the changes to the recommendations in 2012

METHODS:

• Data sources
  • Truven Health Analytics Marketscan Commercial databases
  • Deidentified patient-level data from employer-sponsored private health insurance
• Population
  • Mothers with private employer sponsored insurance delivered between 2009 and 2017
• Study design and data analysis
  • Pertussis hospitalization: Defined as inpatient admission with report of a pertussis-related code
  • Monthly pertussis hospitalization rates: Calculated by dividing the total number of hospitalizations with a pertussis diagnosis in the first 2 months of life by the total number of infants younger than 2 months during a given month
  • Risk ratios (RRs) and 95% CIs for infant pertussis hospitalizations were calculated to compare 2 different time periods
    • 2009-2012 period
    • 2013-2017 period
• Primary outcome
  • Pertussis hospitalization occurring between the date of birth and 2 months of age

RESULTS:

• 1,921,892 infants
• The rate of pertussis hospitalization decreased in the 2013-2017 period, compared to the 2009-2012 period
  • 2009-2012
    • 8.4 per 100,000 infants (95% CI, 7.2 to 9.7 per 100,000; 177 of 2.1 million infants)
  • 2013-2017
    • 3.3 per 100,000 infants (95% CI, 2.6 to 4.3 per 100,000; 57 of 1.7 million infants)

CONCLUSION:

• Authors acknowledge limitations of this study including
  • These patients were all insured and therefore results may not be generalizable
  • Due to nature of the data, maternal Tdap vaccinations status was unknown relative to the infants
• However, these results suggest that the recommendations has had an important impact on young infant pertussis infection rates
• The authors state

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

Learn More – Primary Sources:

Trends in Infant Pertussis Hospitalizations in the United States, 2009-2017

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