European Medical Agency (EMA) is reviewing reports of a rare nerve-degenerating disorder in people who received AstraZeneca Plc’s (NASDAQ: AZN) COVID-19 vaccine, raising new questions about potential side effects of the shot.

What Happened: As part of a regular review of safety reports for the vaccine, the safety committee of EMA is analyzing data provided by AstraZeneca on cases of Guillain-Barre syndrome (GBS). However, it did not specify the number of cases.

The regulator said GBS was identified as a possible adverse event that needed to be specifically monitored during the vaccine’s conditional approval process, adding it had requested more detailed data on the cases from AstraZeneca.

However, researchers have found that the chances of developing GBS after vaccination are extremely small.

GBS is a rare neurological condition in which the body’s immune system attacks the protective coating on nerve fibers. Most cases follow a bacterial or viral infection.

The European Medical Agency is also looking into reports of heart inflammation with Pfizer Inc (NYSE: PFE) - BioNTech SE’s (NASDAQ: BNTX) vaccine and Moderna Inc’s (NASDAQ: MRNA) shot.

It said there was no indication at present that these cases were due to the vaccines.

In addition to seeking more data on heart inflammation, Pharmacovigilance Risk Assessment Committee (PRAC) added a new side effect to Pfizer’s vaccine label for facial swelling in people with a history of injections with dermal fillers.

Why It Matters: “PRAC considered that there is at least a reasonable possibility of a causal association between the vaccine and the reported cases of facial swelling in people with a history of injections with dermal fillers (soft, gel-like substances injected under the skin),” the agency said.

The committee said it’s updating the warning on the Johnson & Jonson (NYSE: JNJ) vaccine and links to thrombosis (formation of blood clots) with thrombocytopenia (low blood platelets) syndrome, advising patients who are diagnosed with thrombocytopenia within three weeks of vaccination to be actively investigated for signs of thrombosis.

Price Action: AZN shares +0.57% at $53.79, JNJ +0.52% at $168.61, BNTX +9.05% at $183.13, PFE +1.02% at $39.59 and MRNA +1.73% at $163.26 during the market trading hours on the last check Friday.