Researchers from Lady Davis Carmel Medical Center in Haifa conducted a nested case-control study involving 3,193,951 patients aged 16 years and older not previously diagnosed as having GBS seen at Clalit Health Services from January 2021 to June 2022. Each patient with GBS in the 6 weeks after infection was matched with 10 randomly selected control patients who did not have GBS.
A chronic illness with no known cure, GBS occurs when the immune system attacks the nerves, causing symptoms such as weakness and tingling in the hands and feet that spreads to the upper body and may lead to paralysis, shortness of breath, abnormal blood pressure, and difficulty walking. Most people recover with few residual effects.
Two thirds of GBS patients reported that they had symptoms of a respiratory or gastrointestinal infection in the 6 weeks before GBS diagnosis. A total of 76 patients were diagnosed as having GBS during follow-up and were matched with 760 control patients. The average age of GBS patients was 56.3 years, and half were women.
Nine of the 76 GBS patients (11.8%) and 18 of 760 controls (2.4%) had tested positive for Covid-19. Eight (10.5%) of GBS patients and 136 (17.9%) controls had been vaccinated against Covid-19, nearly all of them with the Pfizer/BioNTech vaccine.
The odds ratios (ORs) for Covid-linked GBS and Covid-19 vaccine administration were 6.30 and 0.41, respectively, according to multivariable conditional logistic regression models. The findings were comparable when Covid-19 infection or vaccine administration occurred in the previous 1 and 2 months, although the vaccination results at 4 weeks weren’t statistically significant.
“While Guillain-Barre is extremely rare, people should be aware that having a Covid infection can increase their risk of developing the disorder, and receiving an mRNA vaccine can decrease their risk,” co-senior author Anat Arbel, MD, said in an American Academy of Neurology news release.
In a related editorial, Dennis Bourdette, MD, of Oregon Health & Science University, and Elizabeth Silbermann, MD, of the Department of Veterans Affairs Medical Center in Portland, Oregon, said the study results may be reassuring to patients hesitant to receive Covid-19 vaccines.
“In addition, it is possible that the mRNA Covid-19 vaccine may itself lower the risk of acquiring GBS,” they wrote. “Regarding research on the risk of GBS, asking whether a vaccine is associated with an increase in the background risk of GBS is not the only question to ask.”
“The more critical question is whether the risk of vaccine-associated GBS is lower than the risk of disease-associated GBS,” they added. “When it comes to risks of GBS following SARS-CoV-2 infection and Covid-19 vaccination, the preventive remedy clearly is not worse than the disease.”