The risk of Guillain-Barré syndrome after COVID mRNA vaccines is low

I keep reading anti-vaccine commentary that Guillain-Barré syndrome had been linked to the COVID-19 vaccines according to a deep dive into the VAERS database. Those of you who read my works know that I am apt to dismiss almost any claim that is based on VAERS. it is not built to show correlation let alone causation between Guillain-Barré syndrome and COVID-19 vaccines.

However, as I have said before VAERS can send a safety signal that should be investigated more thoroughly. And that’s what a vaccine research team did — they went to a better vaccine safety database and performed a thorough study. And what they found is that the COVID-19 mRNA vaccines, from Pfizer and Moderna, were not linked to Guillain-Barré syndrome. However, they did find a link to the JNJ COVID-19 vaccine, which confirms what was being discussed a few months ago.

Let’s take a look at this study so that we can at least partially debunk anti-COVID-19 vaccine claims.

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What is the Guillain-Barré syndrome?

Guillain–Barré syndrome (GBS) is a rapid-onset muscle weakness caused by the immune system damaging the peripheral nervous system

The initial symptoms usually develop between a few hours to a few weeks and include weakness or a tingling feeling in your legs. The feeling can spread to your upper body. In severe cases, the patient can become almost paralyzed. This is life-threatening.

The cause of GBS is unknown, although the underlying mechanism involves an autoimmune disorder, which describes a condition where the body’s immune system mistakenly attacks the peripheral nerves. Sometimes, GBS appears to be triggered by infection, although surgery and, very rarely, vaccination.

Guillain-Barré syndrome can be treated with intravenous immunoglobulins or plasmapheresis, with good chances for full recovery in the majority of individuals. However, recovery may take weeks to years, with about one-third suffering some permanent weakness. Approximately 7.5% of those affected by GBS will die.

Just to be clear, Guillain–Barré syndrome is rare, at one or two cases per 100,000 people every year.

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The Guillain-Barré syndrome after COVID-19 vaccines paper

In a paper published on 26 April 2022 in JAMA Network Open by Nicola P Klein and colleagues, the researchers examined patient records after 15.1 million doses of COVID-19 vaccines were given to patients in the Vaccine Safety Datalink (VSD, see Note 1). They calculated an unadjusted incidence rate of Guillain-Barré syndrome 1 to 21 days after receiving one of the COVID-19 vaccines.

The study evaluated data from 7.9 million people, ages 12 and older, who received either the JNJ, Pfizer, or Moderna vaccines (including mRNA vaccine doses 1 and 2) from December 2020 through November 2021. The outcome was Guillain-Barré syndrome with symptom onset after vaccination, confirmed by medical record review.

Overall, 15,120,073 COVID-19 vaccine doses were administered to 7,894,989 individuals, including 483,053 Johnson & Johnson, 8,806,595 Pfizer, and 5,830,425 Moderna doses. Patients had a mean age of 46.5 and 53.8% of doses were received by women. Rate ratios (RRs) comparing Guillain-Barré risk after vaccination were adjusted for age, sex, race and ethnicity, site, and calendar day.

Here are the key results:

  • Overall, 15,120,073 COVID-19 vaccine doses were administered to 7,894,989 individuals, including 483,053 Johnson & Johnson, 8,806,595 Pfizer, and 5,830,425 Moderna doses. Rate ratios (RRs) comparing Guillain-Barré risk after vaccination were adjusted for age, sex, race and ethnicity, site, and calendar day.
  • Eleven cases of Guillain-Barré syndrome were confirmed after the JNJ vaccine. The adjusted RR on days 1 to 21 compared with days 22 to 42 after the JNJ vaccine was 6.03 (meaning there was 6X the risk of Guillain-Barré syndrome in the first three weeks after the vaccine was given.
  • Thirty-six cases of Guillain-Barré after the COVID-19 mRNA vaccines were observed. The adjusted RR on days 1 to 21 versus days 22 to 42 was 0.56 which means, technically, that there was a 44% reduction in risk of GBS compared to essentially background (GBS usually manifests itself within a few days of a vaccination, if there is a link).
  • The incidence rate of confirmed Guillain-Barré syndrome after receiving the JNJ vaccine was 32.4 per 100,000 person-years, which is significantly higher than the background rate of 1-2 per 100,000 person-years.
  • The incidence rate of confirmed Guillain-Barré syndrome after receiving either of the COVID-19 mRNA vaccines was 1.3 per 100,000 person-years, which is very similar to the background rate.
  • The JNJ vaccine carried a 20X higher risk for Guillain-Barré than the mRNA vaccines.

The study did have some limitations. The numbers of Guillain-Barré syndrome identified after the JNJ vaccine was so low that it had reduced statistical power and wide confidence intervals. In addition, those who received the JNJ vaccine may differ as a group from those who got the mRNA vaccines. One last thing, the background rate for GBS may be different during this pandemic than it had been pre-pandemic — no studies have been published that describe the incidence of GBS after a COVID-19 infection.


This is the type of study that meets the highest standards of vaccine research. It uses a large number of patients (7.9 million), examining the risk of Guillain-Barré syndrome post-COVID-19 vaccines using real medical records, not anecdotal statements like we find on VAERS.

And what we know is that there is probably no link between COVID-19 mRNA vaccines and Guillain-Barré syndrome. On the other hand, there is weak evidence that seems to confirm that the JNJ vaccine is linked to GBS.

I know most of the readers of this blog are fully vaccinated against COVID-19, so you’re thinking “why are you writing this stuff.” It’s because the pandemic is not going away apparently, and if I can alleviate one more concern about the vaccines, I’ll write about it. Or maybe one of you heard a family member won’t get the vaccine because of GBS, and you can tell them to relax.

I’m just here to present the science as best as I can.


  1. The Vaccine Safety Datalink, or VSD, is a large database of medical data which includes vaccination histories, health outcomes, and subject characteristics. The VSD database contains data compiled from surveillance on more than seven million people in the United States, including about 500,000 children from birth through the age of six years. It is the database preferred by real vaccine researchers. As noted by lead author Nicola Klein:

In the Vaccine Safety Datalink, eight integrated health systems contribute data in collaboration with the CDC. We have full access to complete medical records and we can actively survey for all sorts of medical encounters and health events after vaccination. We know our underlying population; we know who is in the denominator and we don’t have to make estimates.


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