AstraZeneca's COVID-19 shot joins the list of vaccines flagged for rare Guillain-Barre syndrome

Two months after the FDA flagged Johnson & Johnson’s COVID-19 vaccine for the rare nerve disorder Guillain-Barre syndrome (GBS) Europe’s drug regulator has done the same for AstraZeneca’s COVID shot.

The European Medicines Agency will now list GBS as a possible and “very rare” side effect of Vaxzevria, which is administered as a two-dose regimen. Of the 592 million doses of the vaccine administered worldwide through the end of July, 833 cases of the nerve-damaging condition were reported.    

Both are adenovirus-based vaccines, as opposed to the mRNA shots offered by Moderna and Pfizer/BioNTech. The J&J and AZ vaccines also have been linked to very rare cases of blood clots that occur alongside bleeding.

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GBS is a condition in which the immune system attacks nerves and can cause temporary paralysis and breathing problems. Along with the warning, the EMA recommends that AZ vaccine recipients should seek medical attention if they feel weakness and paralysis in the extremities. 

Both the FDA and EMA have said that the benefits of the adenovirus vaccines outweigh the risks.

GBS also has been linked to other vaccine types. Earlier this year, the FDA required GlaxoSmithKline to include a warning about the condition as a potential side effect of its highly successful shingles shot, Shingrix. The condition also has been associated with the H1N1 pandemic flu vaccine.

GBS most commonly occurs after an infection with a virus or bacteria. About 3,000 to 6,000 people per year develop the syndrome, according to the CDC.

As for AstraZeneca, the news is another bit of adversity for its troubled shot, which has been steeped in controversy over its safety. The company also has come under scrutiny for failing to live up to supply pledges for the shot. Additionally, in its attempt to gain emergency use approval for the vaccine in the United States, AZ presented misleading trial data, delaying the process further.

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AZ had little experience with vaccines prior to the pandemic. In recent weeks, the company has reportedly considered opting out of the vaccine business.

Despite its woes, Vaxzevria remains a force in the pandemic fight, especially in lesser-developed countries as AZ ships approximately 200 million doses of the shot per month.