EMA recommends restrictions on Pandemrix

On 21st July 2011 the European Medicines Agency (EMA)  recommended restrictions on the use of Pandemrix. 

Narcolepsy UK were indundated with emails and telephone calls requesting further information.  The following has been provided by John Cherry.

Don’t Panic!

We have been a little overwhelmed today with people wanting to know answers about the EMC report on Pandemrix and narcolepsy. Can I just say if you didn’t get through or I have not responded yet, please be patient. I am working through the 100 plus emails as fast as I can but they keep arriving!

Some general points that might answer most of your questions

The 6 to 13 fold increase in narcolepsy was only found in Finland and Sweden. This is a not a worldwide increase – despite what the BBC, The Mail and The Sun reports. I have contacted all of them to ask for clarifications to be printed. Let me just say this in plain speak; if you had Pandemrix in the UK and are over the age of 20 you are no more likely to get narcolepsy than you were before you took the vaccine. If you are between 4 and 18 in the UK you do have a slightly higher risk of getting narcolepsy but it is nowhere near 6 fold. Also most cases of narcolepsy were discovered between six weeks and six months after vaccination so the majority of people will have been discovered by now.

Despite what you might have read about genetics and narcolepsy I am unaware of any new information suggesting a renewed genetic link. Genetics and narcolepsy is a very complicated area. We are aware that DQB1*0602 HLA marker has been found in 80% of those with narcolepsy and 20% of the general population but having the marker does not mean that you will get narcolepsy. Only 10% of those with narcolepsy have a direct family involvement with the condition. Genetics alone are not sufficient to cause narcolepsy.

I don’t know of any new research that would suggest the present narcolepsy causes are unclear; despite what the BBC might say! What the BBC meant to say was that the trigger for narcolepsy is unclear, which is absolutely correct. We don’t know why the Trib 2s attack the brain but we do know that they do and this is the main cause of narcolepsy.

Do mumps, measles, and hormonal changes cause narcolepsy? We don’t know; if we did know we would be able to help prevent people getting narcolepsy. Hormonal changes, measles, mumps, streptococcal infection have all been suggested in the past; as has passive smoking, insecticides and printing ink. Lots of things are being looked at, but to date, no clear cause has been found and to suggest otherwise is untrue.

What did the EMA report say?

In all honesty not a lot that we didn’t know. First of all it wasn’t the EMA but the European Medicines Agency’s Committee for Medicinal Products for Human Use (CHMP), a minor point for most but it irritates me! The CHMP also took advice from a specially convened meeting of experts in fields such as pediatric neurology, vaccinology, immunology, sleep disorders, infectious diseases, epidemiology, as well as experts from Health Canada, the World Health Organization (WHO) and the ECDC, to consider the latest available data regarding the possible link between Pandemrix and narcolepsy. Quite a group.

The CHMP considered that the studies on Pandemrix in Finland and Sweden were well designed and the results show an association between Pandemrix vaccination and narcolepsy in children and adolescents in those countries. The results indicate a six- to 13-fold increased risk of narcolepsy with or without cataplexy in vaccinated as compared with unvaccinated children and adolescents in Sweden and Finland. This risk increase has not been found in adults (older than 20 years). A similar risk has not been confirmed but cannot be ruled out in other countries.

The Committee thought that the vaccine is likely to have interacted with genetic or environmental factors which might raise the risk of narcolepsy, and that other factors may have contributed to the results. There are several initiatives being developed across the EU to further investigate this association. Exposure to specific infectious diseases (including H1N1) at different ages, particularly upper respiratory infections, may have contributed to the observations in the Nordic area. The CHMP considered that it would be helpful if ongoing epidemiological studies seek to address this question.

The CHMP stressed that further research is necessary

It recommended that in persons under 20 years of age Pandemrix may only be used if the recommended seasonal trivalent influenza vaccine is not available and if immunisation against H1N1 is still needed (e.g. in persons at risk of the complications of infection). The CHMP confirmed that overall the benefit-risk balance of Pandemrix remains positive.

So not much that is new. Yes Pandemrix probably had an effect on narcolepsy numbers, but not by itself. The recommendation that if seasonal influenza vaccine is not available and immunisation against H1N1is still needed that Pandemrix might still be used is interesting. I should stress that this would only be used if H1N1 comes back at us this winter. Pandemrix by itself would have no effect on seasonal influenza as it is a monovalent vaccine – one that only works on one virus.