What are the potential complications of administering Boostrix (Tetanus, diphtheria, and pertussis vaccine) to a pregnant woman within a year of a previous dose?

Complications of Receiving Boostrix in Consecutive Pregnancies

Administering Boostrix (Tdap) to a pregnant woman within one year of a previous dose is generally safe with minimal risk of serious complications, though there may be increased local injection site reactions. 1

Safety of Repeat Tdap Administration During Pregnancy

• Receiving Tdap during consecutive pregnancies has been studied, with data showing no significant increase in serious adverse events for either mother or infant 1
• The Advisory Committee on Immunization Practices (ACIP) has concluded that the potential benefit of preventing pertussis morbidity and mortality in infants outweighs the theoretical concerns of possible adverse events in pregnant women receiving repeat Tdap vaccination 1
• Studies of closely spaced doses of tetanus toxoid-containing vaccines (within 2 years) in non-pregnant individuals found no serious adverse events, suggesting similar safety in pregnant women 1

Potential Complications

Local Reactions

• The most common adverse events are injection site reactions including:
  • Pain (reported in 84-88% of recipients) 2
  • Erythema (redness) at injection site (23-30%) 2
  • Swelling at injection site (20-23%) 2
• These local reactions may be more pronounced with repeat doses due to pre-existing antibodies 1

Systemic Reactions

• Systemic reactions that may occur include:
  • Myalgia (muscle pain) (53-60%) 2
  • Headache (38-41%) 2
  • Malaise (29%) 2
  • Fever (4-7%) 1, 2
• The frequency of these reactions with a second dose is similar to that after the first dose 1

Theoretical Risk of Severe Local Reactions

• A theoretical risk exists for severe local reactions (such as Arthus reactions or whole limb swelling) in women who receive multiple doses during closely spaced pregnancies 1
• These hypersensitivity reactions have historically been associated with vaccines containing tetanus toxoid when administered frequently 1
• However, modern vaccine formulations contain lower concentrations of tetanus toxoid, likely reducing this risk 1

Pregnancy and Birth Outcomes

• Studies have found no increased risk for adverse pregnancy outcomes with Tdap administration during pregnancy, including:

  • No increased risk of major malformations 1
  • No increased risk of stillbirth 1
  • No increased risk of preterm birth 1
  • No increased risk of small for gestational age infants 1
  • No increased risk of hypertensive disorders 1

• One study observed a slight increase in the risk for chorioamnionitis, but this was not associated with increases in preterm or small for gestational age births 1

Clinical Considerations

• When administering Tdap in consecutive pregnancies:

  • Obtain a history to exclude women with moderate or severe adverse reactions to previous doses 1
  • The benefit of protecting the infant from pertussis outweighs the theoretical risks of repeat vaccination 1
  • Most women would receive only 2 Tdap doses, as the interval between pregnancies is typically longer than one year 1
  • Proper immunization technique, including appropriate needle length and standard routes of administration, can minimize adverse events 1

• ACIP has recognized the need for ongoing safety studies of severe adverse events when Tdap is given during subsequent pregnancies 1

Important Caveats

• Pregnant women should be informed about the lack of extensive data on multiple Tdap doses during closely spaced pregnancies 1
• Providers should report any adverse events following vaccination to the Vaccine Adverse Event Reporting System (VAERS) 1
• The timing of vaccination during pregnancy (preferably during the third trimester) is important for optimal antibody transfer to the infant 1
• The risk of pertussis in young infants is significant, and maternal vaccination is the most effective strategy to protect newborns too young to be vaccinated 3, 4