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expert reaction to EMA adding Guillain-Barré syndrome as a very rare side-effect of the Oxford-AstraZeneca COVID-19 vaccine (Vaxzevria) in the product information

The European Medicines Agency (EMA) has updated the product information of the Oxford-AstraZeneca COVID-19 vaccine (Vaxzevria) to include Guillain-Barré syndrome (GBS) as a side effect.


Prof Ian Douglas, Professor of Pharmacoepidemiology, London School of Hygiene & Tropical Medicine, said:

“Earlier this year, cases of Guillain Barre syndrome emerged in conjunction with the AZ vaccine, along with other COVID vaccines, notably the Janssen vaccine which uses a similar adenovirus platform.  Since then, this possible side effect has been under close scrutiny by medicines regulators.

“Today’s announcement by the EMA suggests a causal association is reasonably likely for the AZ vaccine, though still not certain, as it is based on spontaneous case reports rather than formal studies.

“Two things I would highlight about this: 1) If causal, this side effect appears to be very rare.  2) Infection with SARS-CoV-2 is itself a known trigger for Guillain Barre syndrome.

“Taken together, I don’t believe this news alters the risk benefit profile of the vaccine.  But it does serve as a helpful prompt for anyone who experiences early signs of Guillain Barre syndrome shortly after receiving a COVID-19 vaccine to seek medical help.  These include numbness, weakness and pins and needles in hands and feet, often becoming worse over a few days.”


Prof Penny Ward, Independent Pharmaceutical Physician, Visiting Professor in Pharmaceutical Medicine at King’s College London, said:

“Guillain Barré Syndrome (GBS) is a rare neurological condition which, if unrecognised, can lead to paralysis of the chest muscles, respiratory failure and death.  Cases of this condition have most commonly been reported to follow infection with a range of common pathogens including GI infections, glandular fever and respiratory viral infections, including influenza.  It has also been reported following COVID.  In these conditions the incidence figure is around 1/100,000 affected patients.

“Much more rarely, the same disorder has been reported in people following vaccination.  Incidence of GBS after influenza vaccination varies from year to year but is commonly thought to occur in ~1-2/1,000,000 vaccine recipients.  GBS has been reported in association with the Janssen vaccine and PRAC updated the prescribing information for that vaccine to include this condition in July.  MHRA have added GBS to the UK prescribing information as disclosed in this week’s vaccine safety update:

“Data shared today by PRAC include the number of GBS cases reported following receipt of Vaxzevria worldwide, suggesting an incidence of ~1-2 per million doses administered.  This incidence figure is much lower than the incidence of GBS reported historically in people with flu.

“Adding the information to the product information is important as it helps prescribers to be aware of this possibility and reminds them to monitor patients reporting symptoms of weakness in their legs/arms and to take appropriate action to prevent disease progression where GBS is suspected.  Similarly providing information for people receiving the vaccine encourages them to report early signs of this disorder to their doctor, so they can be promptly investigated and treated.  Treatment of early stage GBS can prevent respiratory failure and lead to recovery in most cases.

“This is another example of appropriate action following ongoing safety surveillance.  Rare serious side effects are unlikely to be observed in clinical trials and for this reason ongoing surveillance of safety is important when new medicines go into widescale clinical use.

“The addition of this very rare potential effect to the product information does not reduce the benefit:risk balance of Vaxzevria vaccination, the benefits of which in preventing severe COVID and its resulting complications, including death, far outweigh the incidence of the very rare possible side effects already reported.”



All our previous output on this subject can be seen at this weblink:



Declared interests

Prof Ian Douglas: “I’ve got grants from and shares in GSK, and I sit on the MHRA’s Pharmacovigilance Expert Advisory Group.”

Dr Penny Ward: “No COIs. I am semi-retired, but I am owner/Director of PWG Consulting (Biopharma) Ltd a consulting firm advising companies on drug and device development. Between December 2016 and July 2019 I served as Chief Medical Officer of Virion Biotherapeutics Ltd, a company developing antiviral treatments for respiratory viral diseases. Previous employee of Roche, makers of tocilizumab (anti IL6 antibody) and CMO of Novimmune, makers of empalumab (anti IFN gamma antibody).”



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