Seroprevalence of Bordetella Pertussis Antibodies and Anti-pertussis Antibody Response After a Single Dose of Tdap in Pregnant Thai Women

Study Overview
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Brief Summary
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This study evaluated the seroprevalence of Bordetella pertussis antibodies and anti-pertussis antibody response after a single dose of reduced-antigen, combined diphtheria, tetanus, and acellular pertussis vaccine (Tdap) in pregnant Thai women. All seronegative participants received Tdap, while seropositive participants were equally randomized into 2 groups. Half of seropositive participants received Tdap and the other half received tetanus-diphtheria (Td) as standard protocol.

Detailed Description
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The primary objective of this study was to determine the seroprevalence of anti-pertussis toxin antibodies (anti-PT IgG) among pregnant Thai women. The secondary objectives were to evaluate antibody response after Tdap vaccination between seronegative and seropositive participants and to compare the different antibody titers at delivery among seropositive participants who received Tdap to those who received tetanus-diphtheria vaccine (Td). The sample size calculation was based on the primary objective. Randomized clinical trial was performed for the latter secondary objective.

Official Title
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Seroprevalence of Bordetella Pertussis Antibodies and Anti-pertussis Antibody Response After a Single Dose of Reduced-antigen, Combined Diphtheria, Tetanus, and Acellular Pertussis Vaccine (Tdap) in Pregnant Thai Women

Conditions
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Pertussis, Pregnancy Related

Intervention / Treatment
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* Biological: Tdap vaccine


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Thai pregnant women age at least 18 years No known underlying disease Singleton pregnancy without maternal or fetal complications Gestational age not more than 20 weeks at the time of recruitment Desired for delivery at Siriraj Hospital Exclusion Criteria: Pregnant women who have any contraindication to Tdap vaccine including History of serious allergic reaction to any components of Tdap vaccine History of seizure or coma after receiving Tdap vaccine in childhood Having an underlying disease involving central nervous system (e.g., epilepsy, Guillain-Barré syndrome) History of serious reactions after receiving Tdap vaccine (e.g., severe pain, severe swelling at the injection site) Recently had Tdap vaccine injection Denied for Tdap vaccine injection

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Experimental<br>A single dose of Tdap vaccine at GA 27 - 36 weeks | Biological: Tdap vaccine<br>* A single dose of Tdap vaccine at GA 27 - 36 weeks<br>|
| No Intervention: Active comparator<br>dT vaccine as standard protocol | |

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The Seroprevalence of Anti-pertussis Toxin Antibodies (Anti-PT IgG) in Pregnant Thai Women | Percentage of participants who were seropositive for anti-pertussis toxin antibodies (anti-PT IgG). The overall number of 129 participants is greater than the number of 42 participants include in the Particiant Flow Module because it was the sample size calculated based on the primary objective, which was the seroprevalence of anti-pertussis antibodies in pregnant Thai women. Randomized clinical trial on 42 seropositive participants was performed for one of the secondary objectives, which was to compare the different anti-PT IgG at delivery among seropositive participants who received Tdap to those who received Td. | Four months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Change From Baseline in Anti-pertussis Toxin Immunoglobulin G Levels Among Seropositive Participants Who Received Tdap to Those Who Received Td |  | Eight months |