Flu vax may be safely co-administered with pertussis-containing vaccine during pregnancy

Administering influenza vaccine concomitantly with pertussis-containing vaccine during pregnancy does not contribute to increased risk of adverse pregnancy outcomes, as reported in a retrospective study.

Researchers used linked data from perinatal and immunization registers and hospitalization data for women with singleton pregnancies in New South Wales, Australia, and their infants. Women were grouped into two: those who received concomitant influenza- and pertussis-containing vaccine administration at 20 weeks of gestation or later (concomitant vaccine group) and those who received pertussis vaccination alone (control group).

Preterm birth, stillbirth, small for gestational age, and low birth weight were the primary outcomes. Secondary outcomes included antepartum haemorrhage, postpartum haemorrhage, chorioamnionitis, pre-eclampsia or eclampsia, prelabour rupture of membranes, and preterm labour.

The analysis included 13,918 singleton pregnancies (6,959 in the concomitant vaccine group and 6,959 in the control group) in women with a mean maternal age at delivery of 31.7 years.

Preterm births occurred in 3.8 percent of pregnancies in the concomitant vaccine group and 4.4 percent in the matched control group. Among the 6,391 pairs of live births delivered at term, 8.8 percent infants in the concomitant vaccine group and 9.9 percent in the control group were small for gestational age and 1.7 percent and 1.6 percent in the respective groups had low birth weight.

There were no significant between-group differences observed in the likelihood of preterm birth (adjusted hazard ratio, 0.83, 95 percent confidence interval [CI], 0.66–1.05), small for gestational age (adjusted odds ratio [OR], 0.87, 95 percent CI, 0.74–1.04), low birth weight (adjusted OR, 0.94, 95 percent CI, 0.66–1.35), and any of the secondary outcomes.