tetano
Editor, Senior Moderator
BMC Infect Dis. 2015 Nov 9;15(1):506. doi: 10.1186/s12879-015-1263-7.
[h=1]Febrile seizures after 2009 influenza A (H1N1) vaccination and infection: a nationwide registry-based study.[/h] Bakken IJ[SUP]1[/SUP], Aaberg KM[SUP]2,[/SUP][SUP]3[/SUP], Ghaderi S[SUP]4[/SUP], Gunnes N[SUP]5[/SUP], Trogstad L[SUP]6[/SUP], Magnus P[SUP]7[/SUP], H?berg SE[SUP]8[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] During the 2009 influenza A (H1N1) pandemic, a monovalent pandemic strain vaccine containing the oil-in-water adjuvant AS03 (Pandemrix?) was offered to the Norwegian population. The coverage among children reached 54 %. Our aim was to estimate the risk of febrile seizure in children after exposure to pandemic influenza vaccination or infection.
[h=4]METHODS:[/h] The study population comprised 226,889 children born 2006-2009 resident in Norway per October 1st, 2009. Febrile seizure episodes were defined by emergency hospital admissions / emergency outpatient hospital care with International Classification of Diseases, Version 10, codes R56.0 or R56.8. The self-controlled case series method was applied to estimate incidence rate ratios (IRRs) in pre-defined risk periods compared to the background period. The total observation window was ? 180 days from exposure day. Among 113,068 vaccinated children, 656 (0.6 %) had at least one febrile seizure episode.
[h=4]RESULTS:[/h] The IRR of febrile seizures 1-3 days after vaccination was 2.00 (95 % confidence interval [CI]: 1.15-3.51). In the period 4-7 days after vaccination, no increased risk was observed. Among the 8172 children diagnosed with pandemic influenza, 84 (1.0 %) had at least one febrile seizure episode. The IRR of febrile seizures on the same day as a diagnosis of influenza was 116.70 (95 % CI: 62.81-216.90). In the period 1-3 days after a diagnosis of influenza, a tenfold increased risk was observed (IRR 10.12, 95 % CI: 3.82 - 26.82).
[h=4]CONCLUSIONS:[/h] In this large population-based study with precise timing of exposures and outcomes, we found a twofold increased risk of febrile seizures 1-3 days after pandemic influenza vaccination. However, we found that pandemic influenza infection was associated with a much stronger increase in risk of febrile seizures.
PMID: 26553258 [PubMed - in process]
[h=1]Febrile seizures after 2009 influenza A (H1N1) vaccination and infection: a nationwide registry-based study.[/h] Bakken IJ[SUP]1[/SUP], Aaberg KM[SUP]2,[/SUP][SUP]3[/SUP], Ghaderi S[SUP]4[/SUP], Gunnes N[SUP]5[/SUP], Trogstad L[SUP]6[/SUP], Magnus P[SUP]7[/SUP], H?berg SE[SUP]8[/SUP].
[h=3]Author information[/h]
[h=3]Abstract[/h] [h=4]BACKGROUND:[/h] During the 2009 influenza A (H1N1) pandemic, a monovalent pandemic strain vaccine containing the oil-in-water adjuvant AS03 (Pandemrix?) was offered to the Norwegian population. The coverage among children reached 54 %. Our aim was to estimate the risk of febrile seizure in children after exposure to pandemic influenza vaccination or infection.
[h=4]METHODS:[/h] The study population comprised 226,889 children born 2006-2009 resident in Norway per October 1st, 2009. Febrile seizure episodes were defined by emergency hospital admissions / emergency outpatient hospital care with International Classification of Diseases, Version 10, codes R56.0 or R56.8. The self-controlled case series method was applied to estimate incidence rate ratios (IRRs) in pre-defined risk periods compared to the background period. The total observation window was ? 180 days from exposure day. Among 113,068 vaccinated children, 656 (0.6 %) had at least one febrile seizure episode.
[h=4]RESULTS:[/h] The IRR of febrile seizures 1-3 days after vaccination was 2.00 (95 % confidence interval [CI]: 1.15-3.51). In the period 4-7 days after vaccination, no increased risk was observed. Among the 8172 children diagnosed with pandemic influenza, 84 (1.0 %) had at least one febrile seizure episode. The IRR of febrile seizures on the same day as a diagnosis of influenza was 116.70 (95 % CI: 62.81-216.90). In the period 1-3 days after a diagnosis of influenza, a tenfold increased risk was observed (IRR 10.12, 95 % CI: 3.82 - 26.82).
[h=4]CONCLUSIONS:[/h] In this large population-based study with precise timing of exposures and outcomes, we found a twofold increased risk of febrile seizures 1-3 days after pandemic influenza vaccination. However, we found that pandemic influenza infection was associated with a much stronger increase in risk of febrile seizures.
PMID: 26553258 [PubMed - in process]