ERF of H1N1 vaccination on Narcolepsy

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Scope

What is the ERF of H1N1 vaccination on narcolepsy?

Definition

Background[1]

  • First suspicion reported in May 2010.
  • 15.8.2010 Swedish medicine agency reports time correlated cluster of narcolepsy with the vaccination programme.
    • 24.8.2010 THL recommends temporary halt in vaccinations until further information is available, except in cases where a doctor has explicitly assessed the risks.
  • In 24.1.2011 57 cases of suspected vaccine related narcolepsy had been reported to THL.
    • 55 cases of narcolepsy and cataplexy symptoms, 2 cases of cataplexy symptoms.
    • 33 female, 24 male
    • Age: mean = 12, median = 11, min = 4, max = 37
    • Mean time after vaccination to onset of symptoms: 52 days
      • min = < 1d, max = 8 months
    • 54 out of 57 cases were 4 to 19 years old.
    • Total narcolepsy cases for 2010: 102
      • From which 62 in ages 4-19
  • Besides Finland, only in Sweden and Iceland has narcolepsy been on the rise (out of 30 countries who widely used Pandemrix).
    • In Iceland incidence increased in the unvaccinated population also.

Data

In 5 to 19-year-olds[1]

  • From reviewed patient records the number of narcolepsy cases in subjects 5 to 19 years old in 2009-2010 was determined to be 60.
    • 52 cases in vaccinated subjects.
    • 8 cases in unvaccinated subjects.
    • ~70% of this age group were vaccinated.
    • Period of observation limited to 1.1.2009-16.8.2010, to rule out media impact (which was not significant according to some sensitivity analysis performed by the work group).
    • Period of observation of vaccinated subjects assumed from the start of the vacination programme (week 44?) until 16.8.2010.
  • The odds ratio according to the report is 9.2 (4.5-21.4, 95% CI).

Adults[1]

  • 40 cases confirmed in 2010, which is less than on previous years.
    • 22 of the cases had been vaccinated.
    • ~43% of population vaccinated

Dependencies

Unit

OR is a dimensionless quantity.

Formula

  • For calculating the erf based on data we have
    • Assumes that the vaccination program finishes instantly.

+ Show code

  • For generating data from given mean and confidence intervals

+ Show code

Result

  • 9.2 (4.5-21.4, 95% CI)

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See also

Keywords

References

  1. 1.0 1.1 1.2 Kansallisen narkolepsiatyöryhmän väliraportti 31.1.2011

Related files

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