Doctor explains latest reaction risk in Johnson & Johnson's COVID-19 vaccine

Officials are looking at only 100 cases out of 12 million Johnson & Johnson shots.


There is a new warning about a potential side effect of the Johnson & Johnson vaccine. The FDA said it could cause a slight increased risk of Guillain-Barre syndrome.

Doctors said this syndrome, a rare neurological condition, is a known side effect of some vaccines and infections. Now it's the second side effect warning placed on the J&J shot.

"It usually will manifest with weakness and that weakness typically begins in the lower extremities and kind of ascends and this is something that requires hospitalization, sometimes specific treatments. Most people eventually do recover from it, but it can be something that is very difficult because of the muscle weakness that has occurred," said Dr. Amesh Adalja, Johns Hopkins Bloomberg School of Public Health.

This syndrome is associated with other vaccines, including the flu shot. It made headlines in 1976 during the swine flu vaccine drive.

"That was something that plagued the whole vaccine roll out program, something that led to the CDC director at the time being fired and a lot of controversy that came back to haunt us in 2009 with that swine flu virus and the vaccination drive," Adalja said.

Adalja said this news coming after the warning this spring about the potential for the J&J vaccine to cause a rare blood clot will further increase those hesitant to get the shot.

"All of that has made the J&J vaccine one that is not as demanded with the same frequency as the Pfizer and Moderna vaccines and that's unfortunate because it's a good vaccine, a safe and efficacious vaccine," he said.

Adalja stresses both of these side effects are extremely rare. Federal health officials are looking into just 100 cases of Guillain-Barre syndrome out of more than 12 million J&J shots. He said the benefits still outweigh the risks.

"I do think in the midst of the pandemic where hundreds of people are still dying every day and tens of thousands of cases are occurring, the J&J vaccine, the risk benefit ratio still strongly favors the use of this vaccine," he said.

Doctors said the fact that they've caught these extremely rare side effects is a signal that these vaccines are being monitored closely for safety.