The Food and Drug Administration (FDA) has approved Adacel® (tetanus toxoid, reduced diphtheria toxoid and acellular pertussis vaccine, adsorbed [Tdap]) for immunization during the third trimester of pregnancy to prevent pertussis in infants younger than 2 months of age.

The approval was based on a re-analysis of data from on observational study of Tdap vaccine effectiveness in the US (ClinicalTrials.gov Identifier: NCT05040802). Adacel was estimated to be 88% (95% CI, 43.8-97.4) effective in preventing pertussis in infants younger than 2 months when administered during the third trimester of pregnancy and at least 14 days before delivery based on data from 101 cases of pertussis in infants younger than 2 months of age (including 5 infants whose mothers received Adacel during the third trimester and ≥14 days before delivery) and 171 controls (including 27 infants whose mothers received Adacel during the third trimester and ≥14 days before delivery).

The FDA also reviewed data from a retrospective passive surveillance study (ClinicalTrials.gov Identifier: NCT00258882) that included women who received Adacel during pregnancy (n=225) and controls (n=675). Findings suggest that the rates of major birth defects and miscarriage in women who receive Adacel within 30 days prior to pregnancy or during pregnancy are consistent with estimated background rates. There were 21 reports of spontaneous abortion (9.3%) and 15 congenital anomalies (6.7%) in the Adacel exposed group, and 102 spontaneous abortions (15%) and 57 congenital anomalies (8.4%) in the control group.

Adacel is administered as a single 0.5mL intramuscular injection. To prevent pertussis in infants younger than 2 months of age, Adacel should be administered to pregnant individuals during the third trimester of pregnancy. Pregnancy outcomes in women exposed to Adacel during pregnancy are monitored through a pregnancy exposure registry. Patients and health care providers are encouraged to contact Sanofi Pasteur at (800) 822-2463 or online at www.sanofipasteurpregnancyregistry.com.

Adacel is also indicated for active booster immunization against tetanus, diphtheria and pertussis in individuals 10 through 64 years of age.

Reference

Adacel. Package insert. Sanofi Pasteur Inc; 2023. Accessed January 11, 2023. https://www.fda.gov/media/119862/download.