Maternal Safety of Trivalent Inactivated Influenza Vaccine in Pregnant Women

Harvard University, Cambridge, Massachusetts, United States
Obstetrics and Gynecology (Impact Factor: 5.18). 03/2013; 121(3):519-525. DOI: 10.1097/AOG.0b013e3182831b83
Source: PubMed


To estimate the risks for medically attended events occurring within 42 days of receiving trivalent inactivated influenza vaccine and to evaluate specific risks of first-trimester vaccination.

This retrospective observational cohort study compared rates of medically attended adverse events in trivalent inactivated influenza-vaccinated and unvaccinated pregnant women in the Vaccine Safety Datalink. Using a Poisson distribution and log link, we calculated maternal adjusted incident rate ratios for composite safety outcomes for the full cohort and the subset vaccinated during the first trimester.

The cohort included 75,906 vaccinated (28.4% in the first trimester) and 147,992 unvaccinated women matched by age, site, and pregnancy start date. In the first 3 days after vaccination, trivalent inactivated influenza vaccine was not associated with increased risk of specified medically attended events, including allergic reactions, cellulitis, and seizures (full cohort adjusted incident rate ratio 1.12, 95% confidence interval [CI] 0.81-1.55; P=.48; first-trimester adjusted incident rate ratio .97, 95% CI 0.53-1.78; P=.93). In the first 42 days, no incident cases of Guillain-Barré syndrome, optic neuritis, transverse myelitis, or Bells palsy were identified. Trivalent inactivated influenza vaccine was not associated with thrombocytopenia (full cohort adjusted incident rate ratio 0.90, 95% CI 0.68--1.19; P=.45; first-trimester adjusted incident rate ratio 0.56, 95% CI 0.22-1.39; P=.21) or an acute neurologic event (full cohort adjusted incident rate ratio 0.92, 95% CI 0.54-1.6; P=.75; first-trimester adjusted incident rate ratio 1.05, 95% CI 0.46-2.38; P=.91).

Receipt of trivalent inactivated influenza vaccine during pregnancy was not associated with increased risk of adverse events in the 42 days after vaccination, supporting its safety for the mother.

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    • "Adverse reactions were not systematically assessed across the studies, but there was no evidence of increase in clinically relevant risk related to influenza vaccination during pregnancy. A big cohort study that focused on the safety of trivalent inactivated influenza vaccine, however, did not find any increased risk of adverse events and adverse obstetric events in the vaccinated mothers, when compared to unvaccinated pregnant women [43, 44]. "
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    ABSTRACT: Objective. To assess the effects of the inactivated influenza virus vaccine on influenza outcomes in pregnant women and their infants. Methods. We performed a systematic review of the literature. We searched for randomized controlled trials and cohort studies in the MEDLINE, Embase, and other relevant databases (inception to September 2013). Two researchers selected studies and extracted the data independently. We used the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach to assess the quality of the evidence. Results. We included eight studies out of 1,967 retrieved records. Influenza vaccination in pregnant women significantly reduced the incidence of influenza-like illness in mothers and their infants when compared with control groups (high-quality evidence) and reduced the incidence of laboratory-confirmed influenza in infants (moderate-quality evidence). No difference was found with regard to influenza-like illness with fever higher than 38°C (moderate-quality evidence) or upper respiratory infection (very-low-quality evidence) in mothers and infants. Conclusions. Maternal vaccination against influenza was shown to prevent influenza-like illness in women and infants; no differences were found for other outcomes. As the quality of evidence was not high overall, further research is needed to increase confidence and could possibly change these estimates.
    11/2013; 2013(2):879493. DOI:10.5402/2013/879493

  • Obstetrics and Gynecology 03/2013; 121(3):503-4. DOI:10.1097/AOG.0b013e318285cf61 · 5.18 Impact Factor
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    ABSTRACT: OBJECTIVE: To compare risks for adverse obstetric events between females who did and did not receive trivalent inactivated influenza vaccine during pregnancy. METHOD: This retrospective, observational cohort study was conducted at seven Vaccine Safety Datalink sites. Pregnancies were identified from administrative and claims data using a validated algorithm. Females vaccinated while pregnant from 2002 to 2009 were matched one-to-two with replacement to unvaccinated pregnant females. Using a generalized estimating equation method with a Poisson distribution and log link, we evaluated the association of trivalent inactivated influenza vaccine with 13 outcomes. Given our large sample size and multiple comparisons (19 contrasts), a cutoff for significance of P<.005 was selected a priori. RESULTS: Our cohort included 74,292 vaccinated females matched on age, site, and pregnancy start date with 144,597 unvaccinated females. We did not observe increased risks within 42 days of vaccination for hyperemesis, chronic hypertension, gestational hypertension, gestational diabetes, proteinuria, or urinary tract infection. Using a risk window from vaccination through pregnancy end, we did not observe increased risks after vaccination for proteinuria, urinary tract infection, gestational hypertension, preeclampsia or eclampsia, chorioamnionitis, puerperal infection, venous complications, pulmonary embolism, or peripartum cardiomyopathy. A reduced risk for gestational diabetes after vaccination was detected (adjusted hazard rate ratio 0.88, 95% confidence interval 0.83–0.93), likely as a result of healthy vaccine bias or earlier detection among vaccinees. CONCLUSION: In this large cohort, influenza vaccination during pregnancy was not associated with increased risks for medically attended adverse obstetric events. LEVEL OF EVIDENCE: II
    Obstetrics and Gynecology 09/2013; 122(3):659-667. DOI:10.1097/AOG.0b013e3182a1118a · 5.18 Impact Factor
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