Johnson & Johnson (JNJ.N) said on Monday it was in discussions with the US Food and Drug Administration about rare cases of a neurological disorder, Guillain-Barré syndrome, that have been reported following vaccination with the Janssen COVID-19 vaccine.

The chance of having Guillain-Barré syndrome occur is very low and the rate of reported cases exceeds the background rate by a small degree, J&J said.

The statement follows a Washington Post report on Monday, which said the FDA was expected to announce a new warning on J&J’s coronavirus vaccine related to a rare autoimmune disorder.

Guillain-Barré syndrome is a rare neurological disorder in which the body’s immune system mistakenly attacks part of its peripheral nervous system, or the network of nerves located outside of the brain and spinal cord.