EMA flags Johnson & Johnson COVID vaccine for rare disorder, passes mRNA shots for one side effect but probes another

Producers of adenovirus-vectored COVID-19 vaccines have had to deal with more questions about rare side effects than those making mRNA COVID-19 vaccines.

Now comes another for Johnson & Johnson, as the European Medicines Agency has recommended a rare type of spinal inflammation, transverse myelitis, be added to the label as a side effect.  

"Rare cases of transverse myelitis have been reported following vaccination with the Johnson & Johnson COVID-19 vaccine," the company said in a statement. "While the chances of experiencing these conditions are very low, the product information of COVID-19 vaccine Janssen will be updated to include important information about the signs and symptoms of transverse myelitis. The company will continue to work with the European Medicines Agency’s (EMA’s) Pharmacovigilance Risk Assessment Committee (PRAC) and health authorities."

The EMA also said that it was looking into cases of capillary leak syndrome, a rare blood condition, reported by recipients of the Moderna COVID-19 vaccine. The disorder can cause swelling and a drop in blood pressure. The EMA noted that six cases have been reported by those who received the Moderna shot.

Yet, on another side effect matter for mRNA vaccines, the EMA said there isn't enough evidence to establish a link between Pfizer-BioNTech's shot, Comirnaty, or Moderna's to multisystem inflammatory syndrome, another rare but serious condition. The disorder can cause inflammation of the brain and vital organs such as the heart, lungs and kidneys.

Moderna did not respond immediately to a request for comment. 

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Rare side effects have been a continuing theme with the J&J and AZ vaccines. Capillary leak syndrome was also investigated in relation to the J&J and AstraZeneca vaccines.

And back in September 2020, a trial of the AstraZeneca COVID-19 vaccine, Vaxzevria—also an adenovirus-vectored vaccine—was put on hold in Europe and the U.S. after a patient in the U.K. developed transverse myelitis. The condition can cause pain, muscle weakness and paralysis. The patient eventually recovered, and the trials were resumed. 

A month later, J&J halted a trial of its shot because of an undisclosed “adverse event.” That trial also was resumed shortly afterward.

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Shortly after the J&J shot was approved, its rollout was paused in April by the FDA as the regulator investigated reports of rare blood clots that occurred alongside bleeding. The following week, the FDA allowed the company to resume distribution of the jab but with a label warning.

Another label warning came for J&J in July, when the FDA flagged the rare nerve disorder Guillain-Barre syndrome. Two months later the EMA did the same for AZ’s COVID-19 vaccine.