ERF of H1N1 vaccination on Narcolepsy
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What is the ERF of H1N1 vaccination on narcolepsy?
- 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.
In 5 to 19-year-olds
- 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 determined significant in some sensitivity analysis).
- 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).
- 40 cases confirmed in 2010, which is less than on previous years.
- 22 of the cases had been vaccinated.
- ~43% of population vaccinated
OR is a dimensionless quantity.
- Assumes that the vaccination program finishes instantly.
<rcode> c(287786,302423,334636) -> pop c(215496,232704,178920) -> vac ((52/as.numeric(as.POSIXct("2010-8-16") - as.POSIXlt(44*7*24*60*60,origin="2009-1-1")))/sum(vac))/ ((8/as.numeric(as.POSIXct("2010-8-16") - as.POSIXct("2009-1-1")))/sum(pop-vac)) </rcode>
- 9.2 (4.5-21.4, 95% CI)
- Kansallisen narkolepsiatyöryhmän väliraportti 31.1.2011