Jonas F Ludvigsson1, Henric Winell2, Sven Sandin3, Sven Cnattingius4, Olof Stephansson5, Björn Pasternak6. 1. Karolinska Institutet, Stockholm, and Örebro University Hospital, Örebro, Sweden, School of Medicine, University of Nottingham, Nottingham, United Kingdom, and Celiac Disease Center, Columbia University College of Physicians and Surgeons, New York, New York (J.F.L.). 2. Karolinska Institutet, Stockholm, and Uppsala University, Uppsala, Sweden (H.W.). 3. Karolinska Institutet, Stockholm, Sweden, and Icahn School of Medicine at Mount Sinai and Seaver Autism Center for Research and Treatment at Mount Sinai, New York, New York (S.S.). 4. Karolinska Institutet, Stockholm, Sweden (S.C.). 5. Karolinska Institutet and Karolinska University Hospital, Stockholm, Sweden (O.S.). 6. Karolinska Institutet, Stockholm, Sweden, and Statens Serum Institut, Copenhagen, Denmark (B.P.).
Abstract
BACKGROUND: There are concerns that influenza vaccine exposure during pregnancy may be associated with increased risk for autism spectrum disorder (ASD). OBJECTIVE: To examine the risk for ASD in offspring of mothers who were vaccinated against influenza A(H1N1)pdm09 ("swine flu") during pregnancy. DESIGN: Population-based cohort study using nationwide registers. SETTING: Seven health care regions in Sweden. PARTICIPANTS: Live births between October 2009 and September 2010, with follow-up through December 2016. In total, 39 726 infants were prenatally exposed to H1N1 vaccine (13 845 during the first trimester) and 29 293 infants were unexposed. MEASUREMENTS: Cox regression was used to estimate hazard ratios (HRs) for the primary outcome, ASD, before and after adjustment for potential confounders. The secondary outcome was autistic disorder (AD). RESULTS: Mean follow-up was 6.7 years in both unexposed and exposed children. During follow-up, 394 (1.0%) vaccine-exposed and 330 (1.1%) unexposed children had a diagnosis of ASD. In adjusted analyses, prenatal exposure to H1N1 vaccination was not associated with a later diagnosis of ASD (adjusted HR [aHR], 0.95 [95% CI, 0.81 to 1.12]) or AD (aHR, 0.96 [CI, 0.80 to 1.16]). The 6-year standardized cumulative incidence difference between the unexposed and exposed children was 0.04% (CI, -0.09% to 0.17%) for ASD and 0.02% (CI, -0.09% to 0.14%) for AD. Restricting the analysis to vaccination in the first trimester of pregnancy did not influence risk estimates (aHR, 0.92 [CI, 0.74 to 1.16] for ASD and 0.91 [CI, 0.70 to 1.18] for AD). LIMITATION: Data on H1N1 influenza infection are lacking. CONCLUSION: This large cohort study found no association between maternal H1N1 vaccination during pregnancy and risk for ASD in the offspring. PRIMARY FUNDING SOURCE: Swedish Research Council.
BACKGROUND: There are concerns that influenza vaccine exposure during pregnancy may be associated with increased risk for autism spectrum disorder (ASD). OBJECTIVE: To examine the risk for ASD in offspring of mothers who were vaccinated against influenza A(H1N1)pdm09 ("swine flu") during pregnancy. DESIGN: Population-based cohort study using nationwide registers. SETTING: Seven health care regions in Sweden. PARTICIPANTS: Live births between October 2009 and September 2010, with follow-up through December 2016. In total, 39 726 infants were prenatally exposed to H1N1 vaccine (13 845 during the first trimester) and 29 293 infants were unexposed. MEASUREMENTS: Cox regression was used to estimate hazard ratios (HRs) for the primary outcome, ASD, before and after adjustment for potential confounders. The secondary outcome was autistic disorder (AD). RESULTS: Mean follow-up was 6.7 years in both unexposed and exposed children. During follow-up, 394 (1.0%) vaccine-exposed and 330 (1.1%) unexposed children had a diagnosis of ASD. In adjusted analyses, prenatal exposure to H1N1 vaccination was not associated with a later diagnosis of ASD (adjusted HR [aHR], 0.95 [95% CI, 0.81 to 1.12]) or AD (aHR, 0.96 [CI, 0.80 to 1.16]). The 6-year standardized cumulative incidence difference between the unexposed and exposed children was 0.04% (CI, -0.09% to 0.17%) for ASD and 0.02% (CI, -0.09% to 0.14%) for AD. Restricting the analysis to vaccination in the first trimester of pregnancy did not influence risk estimates (aHR, 0.92 [CI, 0.74 to 1.16] for ASD and 0.91 [CI, 0.70 to 1.18] for AD). LIMITATION: Data on H1N1 influenza infection are lacking. CONCLUSION: This large cohort study found no association between maternal H1N1 vaccination during pregnancy and risk for ASD in the offspring. PRIMARY FUNDING SOURCE: Swedish Research Council.
Authors: Azar Mehrabadi; Linda Dodds; Noni E MacDonald; Karina A Top; Eric I Benchimol; Jeffrey C Kwong; Justin R Ortiz; Ann E Sprague; Laura K Walsh; Kumanan Wilson; Deshayne B Fell Journal: JAMA Date: 2021-06-08 Impact factor: 56.272