A descriptive study of vaccinations occurring during pregnancy, 2002-2006 [abstract]
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Background/Aims: Trivalent influenza vaccine (TIV) is the only vaccine recommended by the Advisory Committee on Immunization Practices (ACIP) for routine administration during pregnancy. The ACIP categorizes remaining vaccines as, "should be considered if indicated", "contraindicated", or with "special/conditional recommendation." The objective of this study was to describe rates of vaccination during pregnancy in seven Vaccine Safety Datalink (VSD) sites. Methods: Using the VSD Pregnancy Algorithm, we identified all pregnancies ending in 2002-2006, including both live births and other birth outcomes (e.g., miscarriages, terminations). We then identified all vaccinations administered during pregnancies occurring in the study period. Results: We identified 595,929 pregnancies and 68,839 vaccinations. The most commonly administered vaccine was TIV, with 58,683 doses and an incidence rate of 98.47 doses per 1,000 pregnancies. TIV was more likely to be administered during the 2nd or 3rd trimester (98.12 per 1,000 pregnancies), versus the 1st trimester (21.98 per 1,000). The total number of indicated vaccinations was 6,743 (11.32 per 1,000) and the most common vaccines in this category were tetanus-diphtheria and hepatitis B (6.65 and 4.31 per 1,000, respectively). Indicated vaccines were more likely to be given during the 1st trimester (7.42 per 1,000) than during the 2nd or 3rd trimesters combined (5.02 per 1,000). A total of 882 contraindicated vaccines were administered during the study period (1.48 per 1,000), and the majority of these were measles-mumps-rubella (MMR) (0.64 per 1,000), varicella (0.49 per 1,000) and live-attenuated influenza vaccine (LAIV) (0.19 per 1,000). The majority of contraindicated vaccines were administered during the 1st trimester (1.02 per 1,000) versus the 2nd or 3rd trimesters (0.58 per 1,000). Discussion: TIV, which is recommended during pregnancy, was the most commonly administered vaccine in our study population. MMR, varicella, and LAIV were the most common contraindicated vaccines administered. With the exception of TIV, other vaccines were more likely to be administered during the 1st trimester of pregnancy, suggesting that vaccinations may occur during a period when either the woman and/or provider are unaware of the pregnancy. Given that some women were also vaccinated during later pregnancy, clearer recommendations and improved provider education may be needed.