According to the results of a study published in Clinical Infectious Diseases, vaccination of pregnant women with the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) vaccine during the third trimester was associated with a high rate of newborns with protective antibody concentrations, regardless of whether vaccination occurred during 27 to 30 weeks or 31 to 35 weeks.
In a prospective cohort study, 88 pregnant women were categorized according to the gestational age at the time of Tdap vaccine administration (27 to 30 weeks or 31 to 35 weeks). Pertussis toxin immunoglobulin (IgG) and pertactin IgG concentrations were evaluated in maternal blood samples collected within 24 hours of delivery as well as in umbilical cord artery samples obtained at the time of delivery. The IgG concentrations were compared between groups and between maternal and umbilical cord pairs.
Pertussis toxin IgG concentrations were higher in umbilical cord serum compared with maternal serum samples (91.6 vs 48.6 enzyme-linked immunoassay [ELISA] units/mL, P <.01). IgG concentrations in maternal serum were significantly correlated with IgG concentrations in umbilical cord serum (P <.01).
Compared with women who received the Tdap vaccine at 27 to 30 weeks, women who received the vaccine at 31 to 35 weeks had no significant difference in maternal serum pertussis toxin IgG concentration (P =.99), cord serum pertussis toxin IgG concentrations (P =.95), or cord serum pertactin IgG concentration (P =.73). Moreover, the time between vaccine and delivery had no impact on any IgG concentration measurements.
Cord serum pertussis toxin IgG concentrations were ≥10 ELISA units/mL in 87% of women vaccinated from 27 to 30 weeks and 97% of mother vaccinated between 31 to 35 weeks (P =.13).
The study investigators concluded that “maternal vaccination against pertussis between 27 and 36 weeks of gestation was associated with a high percentage of newborns with protective pertussis antibody concentrations. Antibody concentrations did not vary by gestational age at the time of maternal vaccination.”
Abraham C, Pichichero M, Eisenberg J, Singh S. Third-trimester maternal vaccination against pertussis and pertussis antibody concentrations. Obstet Gynecol. 2018;131:364-369.