Safety of influenza vaccination during pregnancy

Review on the effects of influenza vaccination during pregnancy on preterm births

“…All studies but one 28 described adjusted odds ratios (aORs) 33,34,44,49 or matched analyses. 35 All the estimated OR were lower than one, however, all the 95% confidence intervals crossed the unit. Sheffield et al reported that premature delivery rates were significantly decreased in the vaccinated group (5% vs. 6%, p D 0.004), however, no adjustment for potential confounders was performed.…”

“…28,32,38,40 An early retrospective study using a database from a large multispecialty clinic in Houston, USA, from 1998 to 2003 compared women who received IIV within 6 months before delivery with non-vaccinated women matched by age at delivery, month of delivery, and type of insurance. 35 Preterm birth analyses after seasonal influenza vaccination Table 2 summarizes the different analyses used in the observational studies and illustrates the adjusted effect estimates reported. Six studies evaluated the impact of seasonal IIV not containing the A/H1N1pdm09 strain on preterm birth rates when administered to pregnant women.…”

“…To adjust for group differences and reduce confounding bias in observational studies 2 main approaches were used: propensity scores 31,34,37 and multiple logistic regression analysis. 10,21,27,29,30,33,35,36,39,[41][42][43][44][45][46][47][48][49] In propensity score analyses probability of vaccination is estimated as a function of available variables and then that score is used as a single matching covariate. The propensity score matching allows comparing the risks after vaccination between cohorts that had the same likelihood of being vaccinated.…”

The safety of maternal immunization

“…8,14,15 Where investigated, few medically-attended adverse events have been identified. 8,15 A number of studies have found no increase in pregnancy complications (e.g., gestational diabetes, pre-eclampsia, caesarean delivery, 16,17 chorioamnionitis) 18 or adverse birth outcomes, including preterm birth, 16,19,20 small for gestational age (SGA) births, [19][20][21][22] congenital anomalies and malformations, 16,23 spontaneous abortion, 24 or stillbirth. 25 Several studies have also shown no adverse effects following first trimester administration of vaccine.…”

Benefits of influenza vaccination during pregnancy for pregnant women

“…Munoz et al 25 conducted a retrospective review of 5 influenza seasons (1998)(1999)(2000)(2001)(2002)(2003) at a large, multidisciplinary clinic in Houston, TX, and compared 225 vaccinated pregnant women with 826 nonvaccinated pregnant women, matched by age, month of delivery, and type of medical insurance. There were no significant differences in medical visits for acute respiratory infections between vaccinated and unvaccinated women, with 23% (51 of 225) of vaccinated women compared with 19% (156 of 826) of unvaccinated women seeking medical care for an acute respiratory infection (P = .24).…”