On May 27, 2013, Andrew Terranella and colleagues from the Centers for Disease Control and Prevention (CDC) studied the efficacy and cost effectiveness of two different strategies to prevent pertussis in infants: 1) immunizing pregnant women with Tdap between 27 and 36 weeks’ gestation, and 2) “cocooning,” which means immunizing mothers and family contacts after the baby has been delivered. This study is important because virtually all deaths from pertussis occur in infants less than 3 months of age. Therefore, pertussis deaths are occurring in those too young to be protected by active vaccination.

The authors found that immunization with Tdap during pregnancy was the preferred strategy. Pregnancy vaccination was better than cocooning for preventing pertussis cases (33 percent vs. 20 percent), pertussis hospitalizations (38 percent vs. 19 percent), and pertussis deaths (49 percent vs. 16 percent). Further, the cost per quality-adjusted life-year saved was substantially less for pregnancy vaccination ($414,000 vs. $1, 173,000).

These results are consistent with the biology of the situation. Babies are better off being protected by circulating antibodies passively acquired from mothers immunized during pregnancy than by counting on all those around them to be immunized.

Terranella A, Asay GR, Messonnier ML, Clark TA, Liang JL. Pregnancy Dose Tdap and Postpartum Cocooning to Prevent Infant Pertussis: A Decision Analysis. Pediatrics. 2013 Jun;131(6):e1748-56.