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Reassuring News for Vaccinating Expectant Mothers During Flu Season

October 27, 2015

Administering the tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis (Tdap) and influenza vaccines on the same day instead of weeks apart during pregnancy did not increase the risks of adverse birth events, reported a recent study.

Investigators reviewed the records of nearly 8,500 pregnant women who received both vaccines concomitantly and 28,380 pregnant women who received the vaccines sequentially. Birth outcome data was available for approximately 4,500 women in both groups.

According to the findings, incidences of fever requiring medical attention or acute illnesses within three to seven days of vaccination did not differ between the groups and serious adverse events rarely occurred. There were also no differences in incidences of premature delivery, low birth weight, and small-for-gestational age newborns between vaccine administrations. The findings matched previous research that showed similar safety profiles for concomitant and sequential administration of the vaccines in nonpregnant individuals, noted the researchers.

Flu vaccines were administered evenly throughout pregnancies, and most often from September through January, according to the study. The Tdap vaccine was given primary in the second or third trimesters, which was in accordance with recommendations issued by the Advisory Committee on Immunization Practices (ACIP). The researchers focused on birth outcomes in women vaccinated at 20 weeks of pregnancy from September to January in order to focus on potential adverse outcomes in women who were eligible for concomitant vaccination.

Expectant mothers are encouraged to receive inactivated influenza vaccine to protect themselves and their fetuses from flu-related mortality and complications. In recent years, pregnant women have also been encouraged to receive the Tdap vaccine between weeks 27 and 36 of pregnancy to maximize the vaccine’s efficacy and to decrease the impact of pertussis in newborns, noted the study.

The researchers said women who are pregnant during the flu season will require both vaccines. The question remains as to whether coadministration or sequential administration is best.

“This study adds to the body of evidence supporting the safety of vaccination during pregnancy,” study lead author Dr. Lakshmi Sukumaran, a medical officer in the Division of Healthcare Quality Promotion at the Centers for Disease Control and Prevention (CDC) in Atlanta. “All vaccine providers, including pharmacists, and pregnant women should be reassured that there does not seem to be an increased risk of adverse events when Tdap and influenza vaccines are given on the same day.”

The study was published online in the journal Obstetrics and Gynecology. It did not receive direct industry support.


 —Dan Cook



1. Sukumaran L, McCarthy NL, Kharbanda EO, et al. Safety of tetanus toxoid, reduced diphtheria toxoid, and acellular pertussis and influenza vaccinations in pregnancy. Obstet Gynecol. 2015;126(5);1069-1074.

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