Quantity and quality of antibodies after acellular versus whole cell pertussis vaccines in infants born to mothers who received Tdap during pregnancy: a randomised trial

Abstract

Background The blunting effect of maternal pertussis immunization during pregnancy on infant antibody responses induced by whole cell pertussis (wP) vaccination is not well-defined.

Methods This randomized controlled trial (NCT02408926) followed term infants born to mothers vaccinated with tetanus-diphtheria-acellular pertussis (Tdap)-vaccine during pregnancy in Thailand. Infants received either acellular pertussis (aP)- or wP-containing vaccine at 2, 4, 6 and 18 months of age. A comparison group comprised wP-vaccinated children born to mothers not vaccinated during pregnancy. Antibodies against pertussis toxin (PT), filamentous haemagglutinin (FHA) and pertactin (PRN) were evaluated using commercial enzyme-linked immunosorbent assays (ELISA). Functionality of antibodies against B. pertussis was measured using B. pertussis growth inhibition assay (BGIA).

Results After maternal Tdap vaccination, 158 infants vaccinated with aP-containing vaccines possessed higher antibody levels (p < 0.001) against all tested B. pertussis antigens post-priming compared to 157 infants receiving wP-containing vaccines. At one-month post-booster, only anti-FHA and anti-PRN antibodies were still significantly higher (p < 0.001) in the aP group. Significantly higher anti-PT and anti-FHA (p < 0.001), but not anti-PRN IgG, were observed among 69 wP-vaccinated infants born to control mothers compared to wP-vaccinated infants of Tdap-vaccinated mothers after primary and booster vaccination. The antibody functionality was higher in all wP vaccinated infants at all times.

Conclusions Maternal Tdap vaccination inhibited more pertussis-specific responses in wP vaccinated infants compared to aP vaccinated infants, and the control group of unvaccinated women had highest pertussis-specific responses, persisting until after the booster dose. Antibody functionality was better in the wP groups.