Statement from a Medicines and Healthcare products Regulatory Agency (MHRA) spokesperson:
Every year, more than eight million doses of flu vaccine are administered across the UK to those aged 65 years and over, with millions more given to healthy younger people and those at higher risk of flu.
As Guillain-Barré syndrome (GBS) can occur naturally across all age groups, and with such high exposure to flu vaccines, it is inevitable that there will be a few cases of GBS after a flu vaccination is given. This association does not necessarily mean the vaccine is the cause. Indeed, for every million people aged 65 years and over who have the vaccine each year, we expect three cases of GBS to occur within six weeks of vaccination by coincidence alone.
Suggestions that flu vaccines may cause GBS can be pinpointed to a very specific type of vaccine given to patients in the USA in 1976. The vaccine was not used in any other countries and a theory was that this risk was due to a contaminant in that particular type of vaccine.
Since then, numerous population-based studies in many countries have looked at whether currently-used flu vaccines may also be a cause of GBS. A couple of these studies have suggested that if there was an association, it would be an extremely small risk – in the order of one case for every million people vaccinated. However, most studies have found no association and, taken together, the evidence is far more suggestive of there being no causal association between flu vaccination and development of GBS.
A review of vaccines and GBS was recently published, which considers this in further detail: https://www.sciencedirect.com/science/article/pii/S0264410X18307989?via%3Dihub. On the other hand, there is good evidence to show that flu-like illness is associated with an increased risk of GBS (https://www.ncbi.nlm.nih.gov/pubmed/19033158), suggesting that flu vaccination may actually protect people from GBS.
If you would like to report a suspected side effect you have experienced after taking a medicine or vaccine, including the flu vaccine, then we would encourage you to do so either via the Yellow Card website https://yellowcard.mhra.gov.uk/ or download the free Yellow Card mobile app from iTunes Yellow Card for iOS or Playstore Yellow Card for Android devices.