More common nervous disorders from coronavirus than from vaccine

There is a small increased risk of two rare neurological disorders in the first weeks after a shot with the AstraZeneca vaccine against Covid-19, and of a brain haemorrhage after the Pfizer vaccine. But after an infection with the coronavirus itself, the risk of these and four other neurological complications is much higher. This is evident from an analysis of the data of more than 32 million Britons that were collected on Monday appeared in the scientific journal Nature Medicine.

The AstraZeneca vaccine concerns the rare but serious Guillain Barré Syndrome (GBS) and facial paralysis (Bell’s palsy). In GBS, nerve cells are damaged by the own immune system. This can lead to, among other things, tingling and less muscle strength, and even to temporary complete paralysis. In Bell’s palsy, the facial nerve is inflamed and the muscles in one half of the face are suddenly paralyzed. Most patients fully recover from these conditions after a few weeks to months.

Huge amount of data

Rare neurological complications have been reported more frequently after vaccination and after SARS-CoV-2 infection. The strength of the UK study is the sheer volume of data.

Researchers from Oxford University, among others, combined the English national vaccination data of more than 32 million adults with national hospital data. For seven neurological complications, they mapped the frequency of these after vaccination with AstraZeneca or Pfizer, and after infection with SARS-CoV-2. They calculated the numbers of the two diseases mentioned, meningitis or spinal cord inflammation, acute damage to the protective insulating layer around nerves, muscle nerve disease and two types of cerebral hemorrhage.

The risk of the rare nervous disorders GBS and Bell’s palsy is very small, but slightly increased in the month after the first dose of the AstraZeneca vaccine. But in the four weeks after an infection with SARS-CoV-2, the risk of these conditions and the other five is much higher. The researchers calculated that there are 38 extra patients with GBS in every ten million people after the AstraZeneca shot. After a SARS-CoV-2 infection, there were many more: 145 extra cases per 10 million infections. After SARS-CoV-2 infection, other neuropathic diseases were also greatly increased: there were 123 extra patients per 10 million with meningitis or spinal cord inflammation, and 163 extra cases per 10 million with muscle nerve disorders.

The researchers repeated the analysis with data from 3 million Scots. There, too, they saw the connection between the first AstraZeneca shot and GBS.

Guillain-Barré syndrome usually develops after a viral infection, such as the flu, cold, or diarrhea. There is also a slightly increased risk with some vaccines against other diseases, such as an American vaccine against shingles, and after the flu shot. But as with Covid-19, the risk of GBS after a flu infection itself is higher than after the flu shot. The other neurological disorders that the British examined can also be caused by viral infections. For example, Bell’s palsy can develop after an infection with the chickenpox virus (varicella zoster virus), which can also cause shingles.

Facial paralysis and GBS are already reported as rare and very rare side effects in the package insert of the AstraZeneca vaccine. GBS is also a very rare side effect of Janssen’s drug. These vaccines are of the same type: they are vector vaccines. It is not yet clear why the condition does occur with vector vaccines and not with the mRNA vaccines (Pfizer and Moderna).

Bell’s palsy and Guillain-Barré Syndrome have also been on the radar at the Lareb side effects center for some time. “It occurs very rarely, so it is noticeable when reports come in,” says director Agnes Kant. A total of 45 reports were received after each of the four vaccines used in the Netherlands. In proportion to the number of people vaccinated with each of the vaccines, it has also been reported here after vaccination with AstraZeneca or Janssen, roughly in 1 in 100,000 vaccinated. “It is much more difficult for reports of brain haemorrhages, because they normally occur much more often,” says Kant. “To get a good picture of that, these kinds of studies are desperately needed.”