Vaccination during pregnancy has been recommended in some countries as a means to protect young infants from severe
infection. Nevertheless, many aspects are still unknown and possible blunting of the infant's immune responses by maternal
antibodies, is one of the concerns with maternal vaccination. We report the first prospective controlled cohort study in women and infants on the effects of using
Boostrix(®), a combined
tetanus,
diphtheria and acellular
pertussis vaccine, during pregnancy. The primary aim was to measure the influence of this booster dose on the titer and duration of the presence of maternal
antibodies in the infants and assess possible interference with infant immune responses. In a controlled cohort study, 57 pregnant women were vaccinated with Tdap
vaccine (Tetanus Diphtheria acellular
Pertussis,
Boostrix, GSK
Biologicals), at a mean gestational age of 28.6 weeks. A control group of pregnant women (N=42) received no
vaccine. Antibody geometric mean concentrations (GMCs) against
tetanus (TT),
diphtheria (DT),
pertussis toxin (PT), filamentous haemagglutinin (FHA) and
pertactin (Prn) were measured with commercial ELISA tests in samples taken preceding maternal vaccination and one month afterwards, at delivery and from the cord blood, and in infants before and 1 month after the primary series of 3
pertussis containing
hexavalent vaccines. Infants born to vaccinated women had significantly higher GMC at birth and during the first 2 months of life for all
vaccine antigens compared to the offspring of unvaccinated women, thereby closing the susceptibility gap for
pertussis in infants. However, blunting was noticed for infant
diphtheria and
pertussis toxin vaccine responses (p<0.001) in the infants from vaccinated women after the primary vaccination schedule (weeks 8,12 and 16). Since
pertussis vaccination has been recommended during pregnancy already, the results of this study support that recommendation and provide additional scientific evidence to document possible interference by maternal
antibodies.