Here's the Deal with the Johnson & Johnson Vaccine and Guillain-Barré Syndrome

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New information is surfacing daily about the COVID-19 vaccines. With that, you might be concerned about reports linking vaccines to certain health conditions or potentially scary side effects. And with the U.S. Food and Drug Administration's new warning linking the Johnson & Johnson (Janssen) vaccine to a rare neurological disorder, it's understandable if you're worried about your health and safety as you navigate your own vaccine experience.

The FDA recently added a warning to the Johnson & Johnson vaccine's fact sheet, noting a "very low" chance of developing Guillain-Barré syndrome after receiving the single-dose shot. New data from the FDA and the Centers for Disease Control and Prevention found that out of 13 million administered doses, there have been roughly 100 preliminary reports of GBS after the one-dose Johnson & Johnson vaccine. Now, health experts are trying to determine if there's a link — but if you're concerned, you can breathe easy knowing that adverse effects to the jab are still extremely rare.

What is Guillain-Barré syndrome?

As mentioned, Guillain-Barré syndrome is an "exceedingly rare" condition in which your immune system attacks nerve cells in your body, potentially leading to muscle weakness and sometimes paralysis, explains Vivek Cherian, M.D., an internal medicine physician affiliated with the University of Maryland Medical System. The condition is so rare, in fact, that GBS affects about 1 in 100,000 people; the CDC notes that between 3,000 to 6,000 people in the U.S. develop Guillain-Barré syndrome each year, and it's most common in adults over the age of 50. (For comparison, the incidence of GBS out of the 13 million administered doses of the J&J vaccine equates to about 1 in 130,000 people.)

GBS often begins with "tingling and weakness starting in your feet and legs and spreading to your upper body and arms," shares Dr. Cherien. "In about 10 percent of people with the disorder, symptoms begin in the arms or face. As GBS progresses, muscle weakness can evolve into paralysis," though, according to the CDC, these severe instances of Guillain-Barré syndrome are rare. Symptoms typically last for a few weeks to several years, leading to permanent nerve damage or even death in some cases, with Dr. Cherian adding that "while there is no cure, there are treatments in the hospital that can help speed up your recovery time" — and most people recover fully, according to the Mayo Clinic — but more on those in a sec.

He also notes that there is no known cause for GBS, but that symptoms often develop following another infection, such as a gastrointestinal bacterial infection or even the flu. There have also been isolated instances of GBS reported after seasonal and swine flu vaccinations, as well as Shingrix, the shingles vaccine, according to the CDC. (Related: What You Need to Know About the COVID Vaccine and Herpes)

All that said, your chances of developing GBS — with or without the J&J vaccine — are still extraordinarily rare. If you want to know more about the potential link and what to look out for, though, read on. (Related: The Johnson & Johnson Vaccine Has Sparked a Conversation About Birth Control and Blood Clots)

What's the link between the Johnson & Johnson vaccine and Guillain-Barré syndrome?

Health experts can't definitively say why or how GBS develops, explains Dr. Cherian, and they won't be able to determine causality for the vaccine, either. "Assuming there is a link — which at this time is not completely clear — we likely won't know why. Even though GBS has been linked to other vaccines or infections, it's still not clear exactly how or why this syndrome develops," he shares.

If all this uncertainty isn't helping to put you at ease, Dr. Cherian says that it's still much safer to get any COVID vaccine that's available to you because "the risks of contracting COVID-19 far outweigh the miniscule chance of having a more severe side effect from the vaccine." In fact, there have been reports of GBS in patients infected with COVID-19 as well. It's also worth noting that, so far, there is no link between the other COVID vaccines — Moderna and Pfizer-BioNTech — and Guillain-Barré syndrome. (Related: How Common Are the Long-Term Effects of COVID-19?)

Though the biological mechanism behind these upticks in GBS is unclear, Dr. Cherian says that "at this time there is not yet enough evidence to establish that the vaccine causes the condition, only that there may be an association. In the grand scheme of things, this does not change anything."

What symptoms should you look out for?

Of the 100 reported cases of Guillain-Barré syndrome after the Johnson & Johnson vaccine, most of them were men in their 50s or older who developed symptoms within 42 days of injection. If you're scheduled for the J&J shot or have recently received yours, Dr. Cherian explains that you should seek medical care if you notice "tingling in your fingers or toes that appears to be getting worse or spreading," adding that, "more alarming signs can include difficulty catching your breath, choking on saliva, or tingling in your feet and toes that rapidly moves up your body."

"The most important thing to remember is the syndrome requires immediate hospitalization particularly because it can worsen rapidly, and the sooner you are able to start treatment, the better chances of recovery," he says. (Related: Everything You Need to Know About COVID-19 Vaccine Side Effects)

If you're diagnosed with GBS, treatment options include plasmapheresis (aka plasma exchange) which essentially involves "filtering part of your blood to remove the antibodies that are involved in attacking the nerves," says Dr. Cherian. This, in turn, helps your body's immune system to stop attacking itself." Another treatment option is intravenous immunoglobulin therapy, which involves an "infusion of antibodies from donors that can essentially suppress your immune system from attacking itself," he adds. Recovery usually takes six to 12 months, though it could take up to three years for some people, according to the Mayo Clinic.

Again, while this all sounds incredibly scary, the chances of needing emergency medical care after your COVID vaccine are still markedly rare. As Dr. Cherian notes, "Most things in medicine involve weighing the benefits versus the risks, and there is no question that the benefits of being vaccinated greatly outweigh any potential risks."

The information in this story is accurate as of press time. As updates about coronavirus COVID-19 continue to evolve, it's possible that some information and recommendations in this story have changed since initial publication. We encourage you to check in regularly with resources such as the CDC, the WHO, and your local public health department for the most up-to-date data and recommendations.