title: Pertussis vaccination during pregnancy in Belgium: Follow-up of infants until 1 month after the fourth infant pertussis vaccination at 15 months of age.
abstract: Vaccination of pregnant women with a pertussis containing vaccine is a recommended strategy in some industrialized countries, to protect young infants from severe disease. One of the effects of the presence of high titers of passively acquired maternal antibodies in young infants is blunting of immune responses to infant vaccination. We present infant immune responses to a fourth pertussis containing vaccine dose at 15 months of age, as a follow-up of previously presented data. In a prospective cohort study, women were either vaccinated with an acellular pertussis vaccine (Boostrix(®)) during pregnancy (vaccine group) or received no vaccine (control group). All infants were vaccinated with Infanrix Hexa(®) according to the standard Belgian vaccination schedule (8/12/16 weeks, 15 months). We report results from blood samples collected before and 1 month after the fourth vaccine dose. Immunoglobulin G (IgG) antibodies against pertussis toxin (PT), filamentous hemagglutinin (FHA), pertactin (Prn), tetanus toxoid (TT) and diphtheria toxoid (DT) were measured using commercially available ELISA tests. Antibody levels were expressed in International Units per milliliter. Demographic characteristics were similar in the vaccine and control group. Before the fourth vaccine dose, significantly lower antibody titers were measured in the vaccine group compared to the control group for anti-Prn IgG (p=0.003) and anti-DT IgG (p=0.023), with a steep decay of antibody titers since post-primary vaccination. One month after the fourth dose, antibody titers were only significantly lower in the vaccine group for anti-PT IgG (p=0.006). For all antigens, there was a rise in antibody titer after the fourth vaccine dose. The present results indicate still a minor blunting effect 1 month after a fourth vaccine dose for anti-PT antibodies. However, a good humoral immune response on all measured antigens was elicited in both groups of children. The clinical significance of such blunting effect is yet unknown. Clinicaltrials.gov identifier: NCT01698346.
authors.affiliation: Centre for the Evaluation of Vaccination, Vaccine and Infectious Disease Institute, University of Antwerp, Belgium. Electronic address: kirsten.maertens@uantwerpen.be.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Maertens
authors.affiliation: National Reference Centre Bordetella, National Reference Centre Toxigenic Corynebacteria, Service Immunology, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium.
authors.forename: Raïssa Nadège
authors.initials: RN
authors.lastname: Caboré
authors.affiliation: National Reference Centre Bordetella, National Reference Centre Toxigenic Corynebacteria, Service Immunology, Scientific Institute of Public Health (WIV-ISP), Brussels, Belgium.
authors.forename: Kris
authors.initials: K
authors.lastname: Huygen
authors.affiliation: Centre for the Evaluation of Vaccination, Vaccine and Infectious Disease Institute, University of Antwerp, Belgium.
authors.forename: Sandra
authors.initials: S
authors.lastname: Vermeiren
authors.affiliation: Interuniversity Institute for Biostatistics and Statistical Bioinformatics (I-BIOSTAT), Hasselt University, Hasselt, Belgium; Centre for Health Economics Research and Modeling Infectious Diseases, Vaccine and Infectious Disease Institute, University of Antwerp, Belgium.
authors.forename: Niel
authors.initials: N
authors.lastname: Hens
authors.affiliation: Centre for the Evaluation of Vaccination, Vaccine and Infectious Disease Institute, University of Antwerp, Belgium.
authors.forename: Pierre
authors.initials: P
authors.lastname: Van Damme
authors.affiliation: Centre for the Evaluation of Vaccination, Vaccine and Infectious Disease Institute, University of Antwerp, Belgium.
authors.forename: Elke
authors.initials: E
authors.lastname: Leuridan
mesh_terms: D000907:Antibodies, Bacterial / Q000097:blood; D001530:Belgium; D015721:Diphtheria-Tetanus-Pertussis Vaccine / Q000627:therapeutic use*; D005260:Female; D018073:Haemophilus Vaccines / Q000627:therapeutic use*; D017325:Hepatitis B Vaccines / Q000627:therapeutic use*; D006801:Humans; D056724:Immunity, Humoral; D007112:Immunity, Maternally-Acquired; D007115:Immunization Schedule; D007117:Immunization, Secondary; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008297:Male; D011054:Poliovirus Vaccine, Inactivated / Q000627:therapeutic use*; D011247:Pregnancy; D011446:Prospective Studies; D017778:Vaccines, Combined / Q000627:therapeutic use; D014917:Whooping Cough / Q000517:prevention & control*
chemical_list: D000907:Antibodies, Bacterial; C505143:Boostrix; D015721:Diphtheria-Tetanus-Pertussis Vaccine; D018073:Haemophilus Vaccines; D017325:Hepatitis B Vaccines; D007074:Immunoglobulin G; D011054:Poliovirus Vaccine, Inactivated; D017778:Vaccines, Combined; C541235:diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae b conjugate-hepatitis B vaccine
keywords: Blunting; Maternal antibodies; Pertussis; Vaccination in pregnancy