To compare pertussis antibody concentrations in maternal venous serum (at the time of delivery) and umbilical cord arterial serum among women vaccinated with the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine from either 27–30 6/7 weeks of gestation or from 31–35 6/7 weeks of gestation.
We conducted a prospective cohort study of pregnant women divided into two groups based on when Tdap was administered: 27–30 6/7 weeks of gestation and 31–35 6/7 weeks of gestation. Paired maternal and umbilical cord samples were obtained at the time of delivery to determine immunoglobulin G (IgG) concentrations to pertussis toxin and pertactin.
Eighty-eight pregnant women were enrolled. Cord serum pertussis toxin IgG concentrations were approximately twice maternal serum pertussis toxin IgG concentrations (91.6 vs 48.6 enzyme-linked immunoassay [ELISA] units/mL, P<.01) and were significantly correlated (Pearson correlation coefficient=0.85, P<.01). There was no significant difference in maternal serum pertussis toxin IgG concentrations (48.6 vs 48.6 ELISA units/mL, P=.99), cord serum pertussis toxin IgG concentrations (92.1 vs 90.7 ELISA units/mL, P=.95), and cord serum pertactin IgG concentrations (798 vs 730 international units/mL, P=.73) between the two groups. Furthermore, there was no correlation between time from vaccination to delivery and these three parameters. Cord serum pertussis toxin IgG concentrations were greater than 10 ELISA units/mL (ie, in the protective range) in 87% and 97% of those vaccinated from 27–30 6/7 weeks of gestation and from 31–35 6/7 weeks of gestation, respectively (P=.13).
Maternal vaccination against pertussis between 27 and 36 weeks of gestation was associated with a high percentage of newborns with antibody concentrations conferring protection and did not vary by gestational age at vaccination.
Maternal vaccination against pertussis in the third trimester is associated with a high percentage of newborns with protective pertussis antibody concentrations.
Hofstra University—Northwell Health System—Staten Island University Hospital, Staten Island, and Rochester General Hospital, Research Institute, Center for Infectious Diseases and Immunology, Rochester, New York.
Corresponding author: Cynthia Abraham, MD, 1176 Fifth Avenue, 9th Floor, New York, NY 10029; email: firstname.lastname@example.org.
Financial Disclosure The authors did not report any potential conflicts of interest.
The authors thank Meagan Sills, Administrative Director of Research at Hofstra University—Northwell Health System—Staten Island University Hospital, for her assistance in acquisition of funding, study approval, and processing of samples.
Each author has indicated that he or she has met the journal's requirements for authorship.