TORONTO -- Health Canada is updating the product information for the Pfizer-BioNTech COVID-19 vaccine to acknowledge very rare reports of Bell’s palsy following vaccination.

In an advisory issued on Friday, the agency said it decided to update the labelling after a small number of people in Canada and internationally reported temporary weakness or paralysis on one side of the face shortly after receiving the vaccine.

The department continues to assure Canadians the vaccines are safe and effective in protecting against COVID-19, and that the benefits of being vaccinated far outweigh the risks.

A released by the U.S. Food and Drug Administration on Pfizer’s clinical trial of the vaccine shows that cases of Bell’s palsy occurred in only four participants out of approximately 43,000, about half of whom received the vaccine and half of whom received the placebo.

The Moderna vaccine label already reflects extremely rare reports of Bell’s palsy, and Health Canada stated it will continue to assess the issue for all COVID-19 vaccines approved in Canada.

Bell’s palsy is described as an episode of muscle weakness or paralysis on one side of the face. It is considered temporary in most cases, with symptoms appearing suddenly and improving after a few weeks..

Health Canada recommends vaccine recipients seek medical attention if they experience any combination of the following symptoms after vaccination:

  • Uncoordinated movement of the muscles that control facial expressions, such as smiling, squinting, blinking or closing the eyelid
  • Loss of feeling in the face
  • Headache
  • Tearing from the eye
  • Drooling
  • Lost sense of taste on the front two-thirds of the tongue
  • Hypersensitivity to sound in the one ear
  • Inability to close an eye on one side of the face

For health professionals, be alert to the signs and symptoms of side-effects following vaccination with COVID-19 vaccines and report any event potentially related to a vaccine to your local public health unit.