Australian GBS cases linked with COVID-19 adenovirus vaccine

Public health

By Geir O'Rourke

17 Nov 2022

Reports of Guillain–Barré syndrome exceeded the expected background for the Vaxzevria ChadOx1-S COVID-19 vaccine, but not for either of the mRNA vaccines on offer in Australia, a case series suggests.

The data was compiled via Victoria’s spontaneous surveillance system, SAFEVIC, and describes 41 cases of GBS reported after a COVID-19 vaccine in the state from February to November 2021.

Each was reviewed by a neurologist to confirm probable GBS diagnosis.

Of those, 38 cases were reported post-vaccination with the AstraZeneca ChadOx1-S vaccine and three after the Pfizer vaccine, Comirnaty BNT162b2.

The third vaccine available in that time Spikevax mRNA-1273, sponsored by Moderna, was linked with no GBS cases reported to the registry.

But only patients receiving the Vaxzevria ChadOx1-S vaccine were at higher risk, with a GBS incidence of 1.85 reports per 100,000 first doses, according to the case series described in the journal Vaccine (link here).

This was significantly higher than the expected rate of 0.39 hospital admissions per 100,000 adults within 42 days of vaccination, the author wrote.

Of the post-ChadOx1-S vaccine reports, the median age at vaccination was 66 years and median onset of symptoms was 14 days following immunisation. There was one death.

The authors stressed the TGA had identified 11 deaths linked to COVID-19 vaccination in total – all post-ChadOx1-S vaccine – including one additional case of GBS, one of immune thrombocytopenia and eight with vaccine induced thrombotic thrombocytopenia (VITT).

“Understanding the pathophysiology and mechanisms behind these serious adverse events raise important questions for the long-term sustainability of adenovirus-vector vaccines in the future, which have saved many more lives from COVID-19 disease,” they added.

“The fatal GBS case in our study was among 19 with an acute GBSDS score of 4 or greater (i.e. at least bedridden or chairbound). Three-quarters of all the GBS cases had ongoing negative impacts three months after their initial presentation.”

Another interesting detail was that over half the patients in the series were female – an anomaly given most epidemiologic studies suggested men were 1.5 times more likely to be affected than women, the authors said.

In a follow-up survey answered by 33 patients (mean 252 days after vaccination, three quarters reported experiencing ongoing negative impacts associated with fatigue.

Participants were asked to rate their health on the day of the questionnaire out of 10 and came back with a median score of even (range 1-9).

Follow-up scores across all metrics were poorest for those with worse GBS symptoms during their initial admission, the authors said.

They added that further research on the topic was needed, given both the importance of adenovirus-vector vaccines in the continuing global COVID-19 vaccination program and continuing development of similar vaccines against ebola, lassa fever, rabies, Middle East respiratory syndrome (MERS), zika, malaria, and tuberculosis.

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