Can the Tdap (Tetanus, diphtheria, and pertussis) vaccine be administered at 29 weeks of gestation?

From the Guidelines

Yes, the Tdap vaccine can be administered at 29 weeks of gestation. The recommended timing for Tdap vaccination during pregnancy is between 27 and 36 weeks of gestation, with the optimal time being early in this window (27-32 weeks) 1. Getting vaccinated at 29 weeks is ideal as it allows enough time for the mother to develop antibodies that can be transferred to the baby before birth. This provides passive immunity to the newborn against pertussis (whooping cough) during the first few months of life when the baby is most vulnerable and before they can receive their own vaccinations.

Key Points to Consider

• The Tdap vaccine is considered safe during pregnancy, and pregnant women should receive one dose during each pregnancy, regardless of their prior vaccination history 1.
• Side effects are generally mild and similar to those experienced by non-pregnant individuals, including soreness at the injection site, mild fever, or body aches.
• The protection this vaccine provides to newborns against pertussis is critical, as this disease can be particularly severe and even life-threatening in infants.
• Recent studies suggest that vaccinating earlier in the 27 through 36-week time period will maximize passive antibody transfer to the infant 1.

Administration Guidance

• The Advisory Committee on Immunization Practices (ACIP) recommends routine vaccination for tetanus, diphtheria, and pertussis 1.
• Women are recommended to receive a dose of Tdap during each pregnancy, which should be administered from 27 through 36 weeks’ gestation, regardless of previous receipt of Tdap 1.
• Administering the Tdap vaccine at 29 weeks of gestation is within the recommended timeframe and is expected to provide optimal protection for the newborn.

From the FDA Drug Label

• immunization during the third trimester of pregnancy to prevent pertussis in infants younger than 2 months of age. (1) The Tdap vaccine can be administered during the third trimester of pregnancy. Since 29 weeks is still in the second trimester but close to the third, and the label does not specify the exact week, a conservative clinical decision would be to wait until the third trimester. However, the label does not directly answer the question regarding administration at 29 weeks.

• The third trimester typically starts at week 28 or 29 of gestation, but this can vary. Given the information provided and the instruction to err on the side of caution, the answer to administering the Tdap vaccine at 29 weeks of gestation is not directly supported by the label. The FDA drug label does not answer the question.

From the Research

Tdap Vaccine Administration at 29 Weeks of Gestation

• The Tdap vaccine can be administered at 29 weeks of gestation, as the recommended timing for maternal Tdap vaccination is between 27 weeks and 36 weeks of gestation 2.
• Vaccination as early as possible in the 27-36-weeks-of-gestation window is recommended to maximize the maternal antibody response and passive antibody transfer and levels in the newborn 2.
• A study found that gestational Tdap immunization between 27 and 30(+6) weeks resulted in the highest avidity of IgG to PT conveyed at delivery as compared with immunization beyond 31 weeks gestation 3.
• Another study found that immunization with Tdap vaccine during the third trimester of pregnancy, compared with no immunization, was associated with higher neonatal concentrations of pertussis toxin antibodies, and that immunization early in the third trimester was associated with the highest concentrations 4.

Safety and Efficacy

• There is no evidence of adverse fetal effects from vaccinating pregnant women with an inactivated virus or bacterial vaccine or toxoid, and a growing body of robust data demonstrate safety of such use 2.
• The Tdap vaccine may be safely given at any time during pregnancy if needed for wound management, pertussis outbreaks, or other extenuating circumstances 2.
• The Advisory Committee on Immunization Practices (ACIP) recommends that all women who are or might be pregnant during the influenza season receive influenza vaccine, and that women receive Tdap during each pregnancy, preferably from 27 through 36 weeks' gestation 5.

Vaccination Coverage

• A study found that among 700 respondents who had a live birth, 54.4% reported receiving Tdap during their pregnancy, and that women who reported receiving a provider offer of vaccination had higher vaccination coverage than did women who received a recommendation but no offer and women who did not receive a recommendation 5.
• Another study found that the median percentage of women with live births who reported any Tdap vaccination was 55.7%, ranging from 38.2% in NYC to 76.6% in Nebraska 6.