Getting Covid infection increases the risk of rare neurological complications in people more than the vaccines, according to a new study.
The study led by researchers from the University of Oxford analysed the healthcare records of more than 32 million people in England.
Their findings, published in Nature Medicine, showed that Covid infection is associated with a greater risk of rare neurological complications such as acute CNS demyelinating events, encephalitis meningitis and myelitis, Guillain-Barre syndrome, Bell's palsy, myasthenic disorders, hemorrhagic stroke and subarachnoid hemorrhage.
The increased risk was found, especially, in the first two weeks after testing positive for SARS-CoV-2.
Among people who received AstraZeneca's Covid vaccine, the team found an increased risk of hospital admission for Guillain-Barre syndrome (15-21 days and 22-28 days), Bell's palsy (15-21 days) and myasthenic disorders (15-21 days).
There were 38 excess cases of Guillain-Barre syndrome per 10 million people given the AstraZeneca vaccine, compared to 145 cases per 10 million after testing positive for Covid-19. However, the risk was not found among those who received the Pfizer shot, the study showed.
People who got Pfizer's Covid jab were at an increased risk of hospital admission for hemorrhagic stroke (1-7 days and 15-21 days). The risk was observed 28 days after vaccination with the Pfizer shot, at an estimated 60 extra cases per 10 people. However, it was not found among those who received the AstraZeneca shot.
There were 38 excess cases of Guillain-Barre syndrome per 10 million people given the AstraZeneca vaccine, compared to 145 cases per 10 million after testing positive for Covid-19Further, the team also found that "Guillain-Barre syndrome and Bell's palsy co-occur in those who received the AstraZeneca vaccine".
"We found that the risk of neurological complications from infection was substantially higher than the risk of adverse events from vaccinations in our population," said Julia Hippisley-Cox, from Nuffield Department of Clinical Neurosciences, University of Oxford, and other researchers in the study.
"Clearly, neurological complications from vaccination and infection reported in this study are rare. However, these rare complications can cause lifelong disability requiring long-term care."
The findings were replicated using an independent national cohort of more than 3 million people from Scotland.
It provided strong support for the association between AstraZeneca vaccine and Guillain-Barre syndrome, but not for Pfizer and hemorrhagic stroke.
The "results provide timely and valuable information that can help to inform clinical decision making, including facilitating earlier diagnosis, as well as resource allocation for health-care provision", the researchers wrote in the study.
The authors of the study also acknowledged limitations of the study such as only risks associated with the first vaccine dose were examined, and only hospital admissions and mortality were included in the examined healthcare data, so patients with milder neurological disease may not have been included.