April 18, 2024

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Guillain-Barré syndrome rises after receiving AstraZeneca COVID-19 vaccine

Guillain-Barré syndrome rises after receiving AstraZeneca COVID-19 vaccine


Guillain-Barré syndrome rises after receiving AstraZeneca COVID-19 vaccine.

Scientists at University College London (UCL) have found in an analysis of NHS data that the first dose of AstraZeneca’s Covid-19 vaccine is linked to the severe neurological disease Guillain-Barré Syndrome (GBS).

There is an association between the small but significant rise in cases.



Guillain-Barré syndrome rises after receiving AstraZeneca COVID-19 vaccine



However, the scientists say it remains unclear what the reason for the link is. In addition, the small number of Guillain-Barré syndrome cases observed appear to be similar to increases previously seen in other mass vaccination campaigns.


The same research team, based at the Queen Square Institute of Neurology at UCL, has previously shown that there is no measurable link between COVID-19 infection and GBS.

This follow-up study was designed to investigate any relationship between COVID-19 vaccination and GBS.


Guillain-Barré syndrome is a rare but serious autoimmune disorder that attacks the peripheral nervous system, usually causing weakness, numbness, pain, and sometimes respiratory paralysis.

GBS often occurs after an infection, especially a gastroenteritis infection called Campylobacter, where the immune system mistakenly attacks the nerves instead of the germs.


GBS is usually reversible, but in severe cases it can lead to long-term paralysis involving respiratory muscles, requiring ventilator support, and sometimes leaving permanent neurological deficits. Early detection by a professional neurologist is the key to proper treatment.


For the study, published in the journal Brain , scientists conducted a population-based study of NHS data to track GBS case rates and vaccination rollout.

In addition, as part of a separate study of UK hospital surveillance data, they looked at the phenotypes (features/symptoms) of reported GBS cases to determine if there were any specific features of COVID-19 vaccine-related GBS.




UK background and analysis

In the UK, the Pfizer COVID-19 vaccine (tozinameran) was launched in December 2020, followed by AstraZeneca (ChAdOx1 nCoV-19) in January 2021, and then Moderna (mRNA-1273) in April 2021.


The researchers observed that between January and October 2021, 996 GBS cases were recorded in the UK’s National Immunoglobulin Database, but there was an unusual spike in GBS reporting between March and April 2021.

In those two months, there were about 140 cases per month, compared to the historical rate of about 100 per month.


To determine whether these cases were linked to vaccination, they linked GBS onset dates to vaccination data for everyone in England’s National Immunisation Management System.


The analysis showed that 198 GBS cases (20% of 966) occurred within six weeks of the first dose of the COVID-19 vaccine in England, equivalent to 0.618 cases per 100,000 vaccinations.

Of these, 176 were vaccinated by AstraZeneca, 21 by Pfizer and 1 by Moderna. In the six weeks following any second dose of the vaccine, only 23 cases of GBS have been reported.


Overall, after the first dose of AstraZeneca vaccine, there were 5.8 overdose cases of GBS per million doses, equivalent to an absolute total of 98-140 overdose cases between January and July 2021.

Neither the first doses of Pfizer nor Moderna nor the second doses of any vaccines showed an excess risk of GBS.


Commenting on the figures, lead author Professor Michael Lunn (UCL Queen Square Institute of Neurology) said: “The number of GBS cases is higher between 2 and 4 weeks after vaccination. Around 24 days after the first dose of vaccine A spike in cases was observed.”


“The first dose of AstraZeneca’s vaccine accounted for most or all of this increase. A similar pattern was not seen after the second dose of any other vaccine or any vaccine.”


In a separate phenotyping study, the researchers used a UK-wide multicentre (four-country) hospital dataset, collecting event data on GBS cases reported by clinicians between January 2021 and November 2021.

At the conclusion of this analysis, the researchers found that no specific clinical features, including facial weakness (of particular interest in the medical literature), were associated with vaccination-related GBS compared with non-vaccinated cases, suggesting that changes from normal How difficult it is to detect vaccination-related cases in the background cases that occur.


Professor Lunn said: “The reason for the association between AstraZeneca vaccination and GBS alone is unclear. There is no strong or possible increased risk of GBS with COVID-19 infection and no increased risk associated with Pfizer vaccination , which means that the COVID-19 spike protein is unlikely to be a causative factor for the increased risk. The viral vectors used to carry nucleic acids in AstraZeneca and similar vaccines may be the cause, but this needs further exploration.”




Historical Background of Vaccine-Related GBS

During the swine flu vaccination campaign in the United States in 1976, there was a small increase in GBS associated with the then new flu vaccine.

At that time, the vaccination campaign was stopped because the risk of developing GBS was statistically higher than background (normal time), although subsequent statistical analysis found that the risk of this association was lower than initially thought.


The excess incidence after the first dose of AstraZeneca’s vaccine was estimated at 5.8 cases per million doses, similar to the 1976 “swine flu” vaccine estimate, and higher than the reported excess cases for modern influenza and yellow fever vaccines (but in the same order of magnitude).

This is far below the 1 in 1,000 GBS incidence associated with Campylobacter jejuni gastroenteritis or Zika virus.


Professor Lunn added: “At the moment we don’t know why vaccines might be causing these very small increases in GBS. It could be that non-specific immune activation occurs in susceptible individuals, but if so, similar risks may apply to all vaccine types. “


“It is therefore logical that simian adenovirus vectors, which are often used to develop vaccines, including AstraZeneca’s, may be responsible for the increased risk.”


“In previous studies, adenovirus has not been strongly associated with GBS, and any association between adenovirus vaccination and GBS has only been reported once. However, in the UK, adenovirus testing is not routinely used in GBS cases ongoing, whether adenoviruses may be part of ‘idiopathic’ (no known etiology) or ‘SARS-CoV-2 negative’ GBS may be the subject of further research.”




Guillain-Barré syndrome rises after receiving AstraZeneca COVID-19 vaccine

(source:internet, reference only)

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