UPDATED: FDA adds second warning to J&J's Covid-19 vaccine on data linking it to rare nerve condition
The J&J Covid-19 vaccine has been linked to a second rare but serious side effect.
The FDA issued a warning Monday afternoon that there are data “connecting the shot to an increased risk” of Guillain-Barré syndrome, a rare condition where the body’s immune system attacks its nerves. The FDA said that there were 100 preliminary reports of the syndrome out of the 12.5 million people who received the vaccine. No such relationship was seen between the Moderna or Pfizer-BioNTech vaccines and the autoimmune condition.
Of those 100 cases, 95 were serious and required hospitalization and that there was one reported death. The agency noted that the vast majority of people with Guillain-Barré syndrome recover and said there was not yet enough data to establish a causal relationship.
The FDA emphasized, as they did when the first rare but serious side effect emerged, that the benefits of the vaccine “clearly” outweigh the risks. The only single-dose Covid-19 vaccine authorized in the US, the shot was shown to be 85% effective at preventing severe disease.
But news of the first side effect appeared to slow both US and global uptake of the vaccine, which public health officials had hoped would reach many people who are less able to access the two-dose mRNA shots.
In April, the FDA and CDC paused the rollout of the vaccine after data linked it to a rare blood clotting disorder. The agencies lifted the hold 10 days later, arguing the benefits still outweighed the risks and that, with greater education and awareness among physicians, the side effects could be caught and managed.
The well publicized side effect, however, appeared to scare many away from taking the vaccine. A Reuters analysis in June found that half of the EU’s J&J supplies had gone unused. The New York Times turned up similar findings in the US. The company’s 12.8 million vaccines administered in the US represent just 8% of the total Americans who have been fully vaccinated and just 7% of the Americans who have been fully vaccinated.
The new side effect, while rare and not yet conclusively linked to the vaccine, may only further hamper uptake for a vaccine that many hoped could provide a crucial tool to reaching hard-to-reach communities and ending the pandemic. It could also provide another blow to the viral vector platform that J&J has built its vaccine business around, as the rival mRNA jabs prove both safer and more efficacious.
J&J’s shot is not the first vaccine to be linked to Guillain-Barré syndrome. The condition often appears after viral infection, but the 1976 swine flu vaccine was also linked to cases among a small number of recipients. In that instance, the CDC reports, the vaccine increased the likelihood of coming down with the syndrome by about 1 instance per 100,000 vaccinations.
A handful of cases of the syndrome have also been linked in Europe to the AstraZeneca-Oxford vaccine, which uses a similar technology to J&J’s.
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