637: No association of malformations with first trimester influenza vaccination

Objective: Seasonal inactivated influenza vaccine (IIV) is recommended during pregnancy to protect both mothers and infants from severe infection. Most studies have evaluated the risk of major structural birth defects in infants associated with prenatal administration of pandemic IIV. Our aim was to estimate the risk in infants associated with prenatal administration of seasonal IIV. Design: Retrospective population-based observational study Setting: Western Australia Population or sample: All pregnant women with a singleton birth from 2012-2016 Methods: 125,866 singleton births were linked to the state’s registers for congenital anomalies and a state prenatal vaccination database. We estimated prevalence ratios (PR) of any major structural birth defect and defects by organ system. Inverse probability treatment weighting factored for baseline probability for vaccination. Bonferroni correction was applied to account for multiple comparisons. Main outcome measures: Prevalence ratios by vaccination and major structural birth defects categories or specific birth defects diagnosed within one month of birth or within six years of life. Results: 3.9% of births had a major structural birth defect. IIV exposure during the first trimester was not associated with diagnosis of any major structural birth defect diagnosed within one month of birth (PR 0.98, 95% CI: 0.77, 1.28) or within six years of life (PR 1.02, 95% CI: 0.78, 1.35). We identified no increased risk in specific birth defects associated with IIV. Conclusions: Results suggest there is no association between maternal influenza vaccination and risk of major structural birth defects. These results support the safety of IIV administration during pregnancy.

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Risk of adverse maternal and foetal outcomes associated with inactivated influenza vaccination in first trimester of pregnancy

Paediatric and Perinatal Epidemiology ◽

10.1111/ppe.12715 ◽

2020 ◽

Author(s):

Hollie A. Speake ◽

Gavin Pereira ◽

Annette K. Regan

Keyword(s):

Influenza Vaccination ◽

First Trimester ◽

First Trimester Of Pregnancy

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Seasonal Influenza Vaccination During Pregnancy and the Risk of Major Congenital Malformations in Live-born Infants: A 2010–2016 Historical Cohort Study

Clinical Infectious Diseases ◽

10.1093/cid/ciaa845 ◽

2020 ◽

Author(s):

Maria Peppa ◽

Sara L Thomas ◽

Caroline Minassian ◽

Jemma L Walker ◽

Helen I McDonald ◽

...

Keyword(s):

Primary Care ◽

Cohort Study ◽

Influenza Vaccination ◽

Congenital Malformations ◽

Seasonal Influenza ◽

First Trimester ◽

Vaccine Uptake ◽

Historical Cohort ◽

Historical Cohort Study ◽

Major Congenital Malformations

Abstract Background Available evidence indicates that seasonal inactivated influenza vaccination during pregnancy protects both the mother and her newborn and is safe. Nevertheless, ongoing safety assessments are important in sustaining vaccine uptake. Few studies have explored safety in relation to major congenital malformations (MCMs), particularly in the first trimester when most organogenesis occurs. Methods Anonymized UK primary care data (the Clinical Practice Research Datalink), including a recently developed Pregnancy Register, were used to identify live-born singletons delivered between 2010 and 2016. Maternal influenza vaccination was determined using primary care records and stratified by trimester. Ascertainment of MCMs from infant primary care records was maximized by linkage to hospitalization data and death certificates. The relationship between vaccination and MCMs recorded in the year after delivery and in early childhood was then assessed using multivariable Cox regression. Results A total of 78 150 live-birth pregnancies were identified: 6872 (8.8%) were vaccinated in the first trimester, 11 678 (14.9%) in the second, and 12 931 (16.5%) in the third. Overall, 5707 live births resulted in an infant with an MCM recorded in the year after delivery and the adjusted hazard ratio when comparing first-trimester vaccination to no vaccination was 1.06 (99% CI, .94–1.19; P = .2). Results were similar for second- and third-trimester vaccination and for analyses considering MCMs recorded beyond the first birthday. Conclusions In this large, population-based historical cohort study there was no evidence to suggest that seasonal influenza vaccine was associated with MCMs when given in the first trimester or subsequently in pregnancy.

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