A(H1N1)v2009: A controlled observational prospective cohort study on vaccine safety in pregnancy

2009 A/H1N1 influenza vaccination in pregnancy: uptake and pregnancy outcomes – a historical cohort study

“…Influenza vaccination is not associated with adverse pregnancy outcomes including fetal death, preterm birth and congenital anomalies. (12)(13)(14)(15)(16)(17) Vaccination may have reduced the risk of influenza-related fetal death during the pandemic. (12) It is essential that extensive data are available on pregnancy outcomes after gestational vaccine exposure in order to inform decisions on vaccination by pregnant women and health professionals, particularly during a pandemic situation.…”

The safety of maternal immunization

“…30 Similar to seasonal influenza vaccine, no adverse birth outcomes were observed following either adjuvanted or nonadjuvanted pandemic vaccination during pregnancy in prospective or retrospective cohort studies. 28,[31][32][33][34] Several studies have suggested there is a reduction in the risk or likelihood of adverse birth outcomes following IIV during pregnancy. 20,25,35 Previous cohort studies have shown seasonal influenza vaccination during pregnancy is associated with a 40-70% reduction in preterm birth, 20,23,36 SGA birth, 20 and stillbirth.…”

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

“…37,39,46 Data on fetal safety of A/H1N1pdm09 monovalent vaccines administered to pregnant women during the 2009/10 pandemic are available from the USA, 30,37 Canada, 43 Argentina, 29 Taiwan 38 and from several European countries. 10,27,31,32,36,40,41,45,48 Unadjuvanted vaccines were used in the North American studies, in France and a study in Taiwan. 30,37,38,40,43,48 The A/H1N1 MF56-adjuvanted formulation was evaluated in Argentina, Italy and the Netherlands.…”

“…10,31,36,41 In Germany and Ireland more than one vaccine formulation was commercially available and recommended for use in the pandemic campaigns. 32,45 The emergence of A/H1N1pdm09 in 2009/10 led to concurrent availability of monovalent vaccine and the seasonal influenza vaccines; with four reports from North America evaluating the birth outcomes when both type of vaccines were administered during the same pregnancy. 37,43,46,47 In the observational studies, as uptake of influenza vaccination could have been biased, adjusting for potential confounders is imperative.…”

“…Four studies did not report adjusted measures for preterm deliveries and only crude numbers and percentages were shown. 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.…”