<scp>Guillain‐Barré</scp> Syndrome in an Australian State Using Both <scp>mRNA</scp> and Adenovirus‐Vector <scp>SARS‐CoV</scp>‐2 Vaccines

Abstract

We read the two recent reports of Guillain–Barré syndrome (GBS) following SARS-CoV-2 vaccination with interest and were inspired to review GBS reports submitted to our enhanced spontaneous surveillance system in Victoria, Australia (SAEFVIC, Surveillance of Adverse Events Following Vaccination in the Community).1-3 Since 21 February 2021, Australia has administered both the AstraZeneca-Oxford (ChAdOx1-S) and Pfizer-BioNTech (BNT162b2) vaccines according to a risk-stratified rollout schedule, initially targeting higher risk groups including healthcare and border workers, as well as residents in aged care facilities (RACF). As of 5 July a total of 1,469,620 doses of the ChAdOx1-S and 882,279 doses of the BNT162b2 vaccines have been administered in Victoria, and SAEFVIC has received 14 reports of GBS after SARS-CoV-2 vaccination, including one report of the bifacial weakness with paresthesia variant reported by Allen et al. (Table1). RACF residents have exclusively received the Pfizer-BioNTech vaccine. All reports were temporally related to the first dose of ChAdOx1-S adenovirus vector vaccine, with symptom onset within 4 weeks of COVID-19 vaccination. Brighton Collaboration case definitions were used to determine diagnostic certainty and severity graded using the GBS Disability Score.4 After excluding one classical case of acute motor axonal neuropathy following Campylobacter jejuni gastroenteritis, we calculated population GBS observed rates and compared these to historical background rates. The observed GBS incidence rate was 1.0 reports per 100,000 doses of ChAdOx1-S vaccine, higher than the expected background rate of 0.61 presentations per 100,000 adult population within 42 days of vaccination (derived from ICD-10-coded admitted episodes). While temporal associations do not imply causality and spontaneous surveillance systems have limitations in capturing all adverse events following immunization, the observed disproportionality of vaccines involved was unexpected, with zero reports to SAEFVIC of GBS after the BNT162b2 mRNA vaccine.5, 6 We do note there are also now case reports of GBS after SARS-CoV-2 mRNA vaccines. Notwithstanding small numbers limiting further interpretation, our data demonstrate an excess of observed cases compared with expected, and disproportionate excess reporting of GBS following ChAdOx1-S vaccine. Continuing vigilance is required, with efforts to maximize ascertainment and reporting, and minimize reporting bias. Spontaneous surveillance systems such as SAEFVIC have an important continuing role to play in monitoring AEFI in the COVID-19 pandemic, moving beyond individual case reports to generate the evidence needed to inform vaccine recommendations at a local and international level. Jim Buttery is a site investigator for non-COVID vaccine related clinical trials for both Pfizer and AstraZeneca. He does not receive compensation for this but his (former) employer Monash Health is compensated for his time. All other authors have no relevant financial or other conflicts of interest pertaining to this submission.

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