COVID Infection Ups Guillain-Barré Syndrome Risk, but mRNA Vaccination Lowers It

There is an increased risk of developing Guillain-Barré syndrome (GBS) among patients infected with SARS-CoV-2 compared with patients not infected; however, the risk for developing GBS is decreased among those who receive mRNA vaccination, specifically the Pfizer-BioNTech vaccine. These are the findings of a study published in Neurology. 

Previous research has indicated there may be increased incidence of GBS since the beginning of the COVID-19 pandemic, as well as after the introduction of COVID-19 mRNA vaccines. 

To determine the possible association between GBS, SARS-CoV-2 infection, and COVID-19 vaccines, researchers conducted a nested-case control study from January 1, 2021, to June 30, 2022. The researchers sourced data from the Clalit Health Services database and the Israeli Ministry of Health’s COVID-19 database. The study included patients (n=836) aged 16 and older who had a positive SARS-CoV-2 PCR or antigen test and were diagnosed with GBS during the follow-up period. For each confirmed patient with GBS (n=76), 10 random control patients (n=760) were selected and matched based on age, gender, and follow-up duration. 

Exposure was defined as a patient receiving a positive SARS-CoV-2 test or any COVID-19 mRNA vaccine within 6 weeks after study entry. Conditional logistic regressions were used to estimate the association between SARS-CoV-2 infection and COVID-19 vaccine with GBS separately, while both exposures were included in a multivariable analysis.

The mean age of patients with GBS and their matched control individuals was 56.3; both groups were comprised of 50% women. Compared with control individuals, there were less low-socioeconomic status (SES; 30.3%) than middle-SES (46.1%) patients with GBS. 

SARS-CoV-2 infection was detected in 2.4% of control cases compared with 11.8% of patients with GBS (crude odds ratio (OR), 6.26; 95% CI, 2.54-15.40). The association between GBS and SARS-CoV-2 infection was estimated to have an odds ratio (OR) of 6.30 (95% CI, 2.55-15.56). 

Exposure to any COVID-19 vaccine was found in 10.5% of patients with GBS and in 17.9% of control patients (crude OR, 0.43; 95% CI, 0.18-1.01). The OR for GBS association with COVID-19 was 0.41 (95% CI, 0.17-0.96). Although the study included all types of COVID-19 mRNA vaccines, almost all patients received Pfizer-BioNTech vaccines except for 2 control patients. 

This study was limited by solely relying on International Classification of Diseases Ninth revision (ICD-9) coding for the diagnosis of GBS, as well as the possibility that some control patients may have had COVID-19 infection. The study was further limited by the possibility of detection bias. 

“[T]his study suggests that SARS-CoV-2 infection is associated with increased risk of GBS, and Pfizer-BioNTech COVID-19 vaccine is associated with decreased risk of GBS,” the researchers concluded. “These findings have important clinical and public health implications and further highlight the benefits of ongoing mRNA-based vaccination programs.”