Study: Guillain-Barré Five Times More Likely in Unvaccinated COVID-19-Positive Patients Than Vaccinated Patients


Patients can sometimes develop Guillain-Barre syndrome after having a recent respiratory illness or digestive tract infection and, in rare cases, after receiving certain vaccines.

The COVID-19 pandemic has been responsible for millions of deaths worldwide over the past 2 years, and the full extent of its impact will likely remain unknown for years. However, it has also mobilized the medical research community, which has dedicated abundant time, talent, and resources to better understanding all aspects of this virus in the interest of effectively countering it.

Epic Research has been conducting studies throughout the pandemic to provide health insights to both the medical community and general public. One of the most recent studies showed that patients who have tested positive for COVID-19 but have not received a vaccine are 5 times more likely to develop Guillain-Barre syndrome (GBS) than COVID-19-positive patients who are fully or partially vaccinated.

GBS is a rare autoimmune disorder in which an individual’s own immune system damages their nerves. The disorder is known to cause muscle weakness and sometimes paralysis, with symptoms lasting from a few weeks to years in severe cases. Most patients that suffer from GBS make a full recovery, although fatal cases have been reported.1

Patients can sometimes develop GBS after having a recent respiratory illness or digestive tract infection and, in rare cases, after receiving certain vaccines. Some evidence suggests that patients might have an increased risk of GBS after having COVID-19 or, very rarely, after receiving a COVID-19 vaccine.2,3

Epic Research investigated whether patients who have received a COVID-19 vaccine or who have had a COVID-19 infection have developed GBS at a higher rate compared to baseline rates in the general population. Analysis shows that unvaccinated patients with a COVID-19 infection are more likely to develop GBS than COVID-vaccinated patients, with a rate of 28 per million for COVID-19-vaccinated patients, and 130 per million for unvaccinated, COVID-19-positive patients.

The use of a dual team approach helps validate important findings and works to quickly disseminate findings to stakeholders in clinical practice and policy. Two independent teams are assigned a topic to explore, with each team completing its research independently using whatever methodologies they deem appropriate. Upon completion, the teams reconcile their findings and collaborate on a brief.

That brief is then reviewed by a panel of subject matter experts for approval before the data are published. Another COVID-related study found that reinfections with the virus were 44% more likely among those who had not been vaccinated.

An additional study, completed in partnership with the Kaiser Family Foundation, examined hospital stay duration among COVID-19 patients. The study showed that in addition to reducing the overall need for hospitalization—and thus the strain on facilities and staff—the COVID-19 vaccine allowed patients who did receive hospital care to recover and leave sooner than patients who were hospitalized without the vaccine.

These studies are completed using Cosmos, a HIPAA-defined limited data set that allows physicians to learn from thousands of other hospitals and clinics—and their patients—on a national scale. Cosmos was created by more than 145 health care organizations that use Epic’s electronic health record system and have consented to this information being used for medical research.

This dataset represents more than 126 million patients across all 50 states and closely aligns with US census demographics. This allows physicians across the county to compare groups of similar patients and assess real-world outcomes to evaluate the best option for their patient. The CDC and FDA both used insights from Cosmos when making recommendations for vaccine rollouts and approvals.

About the Author

Jeff Trinkl, MD, is director of Clinical Informatics at Epic Research.


  1. Guillain-Barre syndrome-Symptoms and causes. Mayo Clinic.Published2018. Accessed January 17, 2022.
  2. Caress JB, Castoro RJ,Simmons Z,etal. COVID-19–associated Guillain-Barré syndrome:The early pandemic experience. Muscle & Nerve. Published online August 11, 2020.doi:10.1002/mus.27024
  3. Coronavirus (COVID-19) Update: July 13, 2021. FDA. Published July 13, 2021.
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