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Background: Live attenuated influenza vaccine (LAIV) is approved for use in eligible individuals 2–49 years of age. The LAIV prescribing information contains warnings against use during pregnancy; however, rare administration during pregnancy does occur.
Objectives: To estimate the rate of LAIV use in pregnant women and describe maternal outcomes after vaccination with LAIV.
Methods: Data from a health insurance claims database that covers approximately 50 million individuals were analyzed over 6 influenza seasons from 2003 through 2009. Any woman 12–49 years of age with claims indicating LAIV receipt and the delivery of a child were included in the analysis. Primary diagnoses for emergency department (ED) visits and hospitalizations occurring within 42 days of vaccination were tabulated. Outcomes were categorized as cardiopulmonary, obstetrical, and other; rates were calculated by the proportion of LAIV recipients with each outcome. Cohort characteristics were summarized using descriptive statistics.
Results: Over the entire study period 834,861 pregnancies were identified, of which 138 (0.017%) were preceded by a claim for LAIV. Twelve percent were ≤18 years, 68% were 19–34 years, and 20% were ≥35 years of age; 15% had a high risk underlying medical condition. Forty-seven percent of all LAIV exposures occurred in the first trimester. Ninety-five percent of deliveries were estimated to be full term. Three hospitalizations and 5 ED visits occurred within 42 days of vaccination; 1 ED visit for bronchitis, 2 hospitalizations for hyperemesis gravidarum and premature labor, and 5 visits/hospitalizations for 5 common medical conditions. All outcomes identified after LAIV exposure occurred at rates similar to rates in unvaccinated pregnant women found in the medical literature.
Conclusions: Administration of LAIV to pregnant women is very rare. In this limited cohort, there was no evidence of significant maternal adverse outcomes following receipt of LAIV.