From the Guidelines
The optimal timing for pertussis immunization during pregnancy is between 27 and 36 weeks gestation, with the ideal window being 27-32 weeks, and vaccinating at around 28-30 weeks appears to provide the highest antibody levels in both the mother and newborn. This recommendation is based on the most recent and highest quality study available, which suggests that vaccinating earlier in the 27 through 36-week time period will maximize passive antibody transfer to the infant 1. The Tdap vaccine contains tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis vaccine, and when administered during this timeframe, maternal antibodies have sufficient time to develop and transfer across the placenta to the fetus, providing passive immunity to the newborn until they can receive their own pertussis vaccinations starting at 2 months of age.
Some key points to consider when administering the Tdap vaccine during pregnancy include:
- Vaccination should be given during each pregnancy, regardless of prior Tdap vaccination history or the interval between pregnancies, as antibody levels wane over time 1.
- If not administered during the optimal window, the vaccine should still be given at any point during pregnancy rather than missing the opportunity for protection 1.
- The strategy of preventing pertussis in newborns through the vaccination of women with Tdap during pregnancy from 27 through 36 weeks’ gestation is 80%–91% effective 1.
- Maternal vaccination is 58% effective in preventing hospitalization among infants infected with pertussis 1.
Overall, the evidence suggests that vaccinating pregnant women with Tdap between 27 and 36 weeks gestation, with a focus on the 27-32 week window, is the most effective way to protect newborns from pertussis, and this recommendation should be followed in clinical practice.
From the Research
Optimal Timing for Pertussis Immunization in Pregnant Women
- The recommended timing for maternal Tdap vaccination is between 27 and 36 weeks of gestation, as stated by the Advisory Committee on Immunization Practices 2, 3.
- Studies suggest that vaccinating pregnant women with Tdap between 27 and 30 weeks of gestation may provide the highest concentration of pertussis-specific antibodies to the newborn 4, 5.
- A study found that gestational Tdap immunization between 27 and 30 weeks resulted in the highest avidity of IgG to PT conveyed at delivery compared with immunization beyond 31 weeks gestation 4.
- Another study found that immunization of pregnant women with Tdap between 27-30 weeks was associated with the highest umbilical cord geometric mean concentrations of IgG to PT and FHA compared with immunization beyond 31 weeks gestation 5.
- A more recent study suggests that prenatal Tdap vaccination reduces the risk of pertussis infections in the infants' first 6 months by 36%, and vaccination soon after 27 weeks of pregnancy ensures vaccination includes those born preterm, who are at highest risk for pertussis 6.
Key Findings
- The optimal timing for Tdap administration is between 27 weeks and 36 weeks of gestation, with some studies suggesting that vaccination between 27 and 30 weeks may be more effective 4, 5.
- Tdap vaccination during pregnancy is safe and effective in reducing the risk of pertussis in newborns 2, 3, 6.
- Preterm infants are at higher risk for pertussis and may benefit particularly from Tdap vaccination soon after 27 weeks of pregnancy 6.