FOI release

Freedom of Information request about the Fluenz Tetra Influenza nasal vaccine (FOI-21-475)

Published 28 June 2021

Thank you for your email dated 2 May 2021, where you asked for information on the following:

• The number of reported cases, annually and by year, of suspected contraction of Narcolepsy following the administering of the Fluenz Tetra Influenza nasal vaccine within the United Kingdom from July 2012 to present.

• The number of reported cases, annually and by year, of suspected contraction of Cataplexy following the administering of the Fluenz Tetra Influenza nasal vaccine within the United Kingdom from July 2012 to present.

The MHRA has received a total of 2892 adverse drug reaction (ADR) reports associated with the Fluenz Tetra vaccine, up to and including 09/05/2021. Of these, the MHRA has received 22 reports of narcolepsy and 18 reports of cataplexy.

Further to your request, I have provided a breakdown, by year, of the numbers of ADR reports of narcolepsy and cataplexy associated with Fluenz Tetra (Table 1.)

Table 1. UK spontaneous ADR reports of narcolepsy and cataplexy associated with Fluenz Tetra.

Fluenz Tetra
Year	Narcolepsy	Cataplexy
2014	1	1
2015	5	5
2016	3	3
2017	1	1
2018	4	2
2019	5	3
2020	3	3
Total	22	18

The MHRA continuously monitors the safety of vaccines through a variety of pharmacovigilance processes including the Yellow Card scheme. As part of our signal detection processes all adverse reaction reports received by the Yellow Card scheme are individually assessed and cumulative information reviewed at regular intervals.

When considering the spontaneous Adverse Drug Reaction (ADR) data, it is important to be aware of the following points:

A reported reaction does not necessarily mean it has been caused by the vaccine, only that the reporter had a suspicion it may have. Each year, millions of doses of routine vaccines are given in the UK alone, and when any vaccine is administered to very large numbers of people, some recipients will inevitably experience illness following vaccination. The fact that symptoms occur after use of a vaccine, and are reported via the Yellow Card scheme, does not in itself mean that they are proven to have been caused by the vaccine. Underlying or concurrent illnesses may be responsible and such events can also be coincidental.

It is also important to note that the number of reports received via the Yellow Card scheme does not directly equate to the number of people who suffer adverse reactions and therefore cannot be used to determine the incidence of a reaction. ADR reporting rates are influenced by the seriousness of ADRs, their ease of recognition, the extent of use of a particular drug, and may be stimulated by promotion and publicity about a drug. Reporting tends to be highest 

Any emerging evidence relating to possible risks associated with vaccines and medicines, is carefully reviewed and, if appropriate, regulatory action would be taken if any serious risks were confirmed.

As these data do not necessarily refer to proven side effects, you should refer to the product information which can be found here: https://www.medicines.org.uk/emc/ for details on the possible side effects of this vaccine.

I hope the information provided is helpful. The MHRA encourages the use of Yellow Card data however wishes to ensure that the data is studied and applied appropriately, and any conclusions/interpretations take into account the above information. For this reason, if you wish to use this information for a publication, we request that you engage with the MHRA during this process and provide a copy of the report.

If you are dissatisfied with the handling of your request, you have the right to ask for an internal review. Internal review requests should be submitted within two months of the date of this response; and can be addressed to this email address.

Yours sincerely,

FOI Team,

Vigilance and Risk Management of Medicines Division