A safety panel of the European drug regulator on Friday recommended adding a rare spinal inflammation called transverse myelitis as a side effect of AstraZeneca's COVID-19 vaccine.

The vaccine has faced several setbacks, including production delays, probes by regulators following rare cases of severe side effects such as blood clots with low platelets, which led to several countries restricting or stopping its use.

The European Medicines Agency's safety committee also reiterated its recommendation of a similar warning to be included for Johnson & Johnson's JNJ.N one-shot vaccine.

The committee, after reviewing data, concluded that a causal relationship between these two vaccines and transverse myelitis is at least a reasonable possibility.

But added that the benefit-risk profile of both vaccines remains unchanged.

Reports of the serious neurological illness was also at the heart of trial halts in the early stages of development for both AstraZeneca and J&J's shots, which are based on similar technology.

The regulator also recommended updating the product information for AstraZeneca's vaccine, regarding rare blood clots following the first shot, to say fewer such side effects were observed after the second dose.

(Reporting by Mrinalika Roy in Bengaluru; Editing by Shinjini Ganguli) ((mrinalika.roy@thomsonreuters.com; within U.S. +1 646 223 8780, outside U.S. +91 806749 8325;))