Maternal pertussis vaccination is associated with higher levels of pertussis

32 Maternal pertussis vaccination is associated with higher levels of pertussis 33 antibodies at birth. We assessed the persistence of pertussis antibodies until 34 primary vaccination in infants whose mothers received Tdap (tetanus, 35 diphtheria, acellular pertussis) vaccine during pregnancy. Infants were born at 36 the Hospital Clinic of Barcelona (Spain) in November 2014. Anti-PT IgG was 37 determined by ELISA at delivery, between the first and second month of life, 38 and estimated at 2 months of age. The study included 37 infants whose 39 mothers received Tdap between 21 and 38 weeks of gestation. Infants 40 presented a decline in GMC of anti-PT IgG between peripartum and follow-up 41 levels, 52.7 (95% CI 34.7–80.2) versus 7.5 (95% CI 4.2–13.3) at 2 months of 42 age (p <0.001). The median half-life of maternal antibodies was 47 days. More 43 than half (51.4%) the infants presented detectable anti-PT IgG before the start 44 of primary infant vaccination. 45 46