Johnson & Johnson’s covid-19 vaccine is reportedly getting a new warning label attached to it, according to the New York Times, following incidents of a rare but serious nerve condition linked to its use known as Guillain-Barré syndrome. The new warning issued by the Food and Drug Administration will not apply to the other two covid-19 vaccines widely available in the U.S., and officials are expected to continue emphasising that the benefits of the J&J vaccine outweigh its potential risks.
Guillain-Barré syndrome (GBS) is a very rare autoimmune condition where the immune system accidentally attacks the body’s nerve cells, leading to symptoms like weakness and tingling that spread along the legs to the upper body and arms and can turn into full paralysis. Symptoms typically get progressively worse in the first two weeks, sometimes to the point of causing a fatal paralysis of the lungs or heart attack. Most people do fully recover within six months, but about a third of sufferers will experience lingering complications.
Why GBS happens is still largely a mystery, but it’s thought that specific infections raise people’s risk of it due to how they stimulate the immune system. The Zika virus, for example, is “strongly associated” with GBS, according to the CDC. Because vaccines also stimulate the immune system, the possibility of GBS linked to vaccination is plausible.
In 1976, for instance, the swine flu vaccine (meant for a feared strain of the flu that came and went with no real danger) was strongly linked to a small increased risk of GBS. There’s also some evidence to suggest seasonal flu vaccination in general may raise the odds of GBS (less so than the 1976 vaccine), but it remains a very low risk eclipsed by the benefits of preventing flu, which is itself a potential trigger for GBS. Up until recently, at least, there had been no indication, even in clinical trials, that any covid-19 vaccines were suspected to have caused GBS.
The new warning is set to be announced by the Food and Drug Administration as early as tomorrow, the New York Times first reported Monday afternoon. According to the NYT, around 100 reports of Guillain-Barré syndrome are suspected to be connected to the single-dose J&J vaccine, collected through the Vaccine Adverse Event Reporting System, or VAERS. These cases have mostly involved men over 50, the typical risk profile of GBS sufferers, who developed it within three weeks of vaccination. Though cases of Guillain-Barré can be expected to happen regularly but rarely in any population, the rate of cases among those vaccinated with the J&J shot is reportedly three to five times higher than it is in the general population. There are an estimated 3,000 to 6,000 cases of GBS in the U.S. every year.
The warning labels will reportedly not affect the Pfizer/BioNTech and Moderna vaccines, both of which are mRNA-based and not adenovirus-based like the J&J shot. The vast majority of vaccinated Americans have received an mRNA vaccine, due to its availability as well as production stumbles with J&J’s supply. Only about 13 million Americans have gotten the J&J vaccine.
Covid-19 itself has also been linked to GBS. But there may be an added factor involved in the risk associated with the J&J vaccine, given the lack of added risk seen with other types of vaccines used widely. Similar to the J&J shot, Oxford University and AstraZeneca’s vaccine uses a delivery method of a neutered adenovirus. Last month, researchers in the UK and India reported seeing an “unusual variant of Guillain-Barre syndrome” linked to the AstraZeneca vaccine. Previously, both the J&J and the AstraZeneca vaccines were uniquely linked to a risk of a rare blood clotting disorder, which similarly led to a warning label placed on them.
These sorts of very rare effects are always a possibility when a new drug or vaccine leaves the clinical trial process and reaches the public, and they have to be evaluated on a case-by-case basis against the benefits of a treatment to see if they still merit wide use. Covid-19 vaccines in general have alleviated a lot of suffering. Just this past week, an analysis by the Commonwealth Fund estimated that these vaccines in the U.S. alone have prevented a quarter-million deaths and a million hospitalisations as of late June.