The optimal gestation for pertussis vaccination during pregnancy – A prospective cohort study.

There is an increasing incidence of pertussis infection in infants too young to be adequately protected via vaccination. Maternal pertussis vaccination during the third trimester of pregnancy is a new strategy to provide protection to newborn infants.
This study sought to determine the optimal gestational window for vaccination in the third trimester.
This prospective study recruited three groups of women; an early vaccination group, vaccinated between 28-32 weeks gestation, a late vaccination group, vaccinated between 33-36 weeks gestation and an unvaccinated control group. Maternal venous blood was taken prior to pertussis vaccination. At birth infant cord blood was collected to determine antibody levels to pertussis toxin (PT), pertactin (PRN) and filamentous hemagglutinin (FHA).
154 women were recruited between April and September 2014. There was no significant difference between maternal PRN and FHA antibody levels amongst the three groups, however, PT was higher in the early compared to late vaccination group (p=0.05). Cord blood antibody levels to PT, PRN and FHA were significantly higher in those born to vaccinated women compared with unvaccinated controls (p<0.001, p=0.001, p<0.001 respectively). Vaccination between 28-32 weeks gestation resulted in significantly higher cord blood PT (4.18.0 vs 3.50 IU/ml, p=0.009), PRN (5.83 vs 5.31 IU/ml, p=0.03) and FHA (5.56 vs 5.03 IU/ml, p=0.03) antibody levels than vaccination between 33-36 weeks gestation. When adjusted for maternal pre-vaccination antibody levels, PT levels in the early versus late vaccination approached significance (p=0.06). PRN levels were significantly higher in the early vaccination group (p=0.003). There was no significant difference for FHA antibody levels between the two groups (p=0.16).
Maternal vaccination during the third trimester is effective in affording higher levels of pertussis antibody protection to the newborn infant. Vaccination early in the third trimester appears more effective than later in pregnancy

Authors:Naidu MA1, Muljadi R2, Davies-Tuck ML3, Wallace EM4, Giles ML5.
Journal:Am J Obstet Gynecol. 2016