I wrote a little bit about this a few weeks ago, when AstraZeneca paused its UK trial of the Oxford vaccine after one subject developed a neurological issue. Sources told the media at the time that the issue in question was transverse myelitis, a disease of the spine. That was the second time AstraZeneca had paused its trial; the first pause, it turned out, was also due to the emergence of a neurological problem in a participant.

That issue, it turns out, was … transverse myelitis, a condition that normally afflicts one in 236,000 people, per the Times. Two participants in an 8,000-member Oxford vaccine trial have now been diagnosed with it.

Uh oh.

Don’t freak out, AstraZeneca says. The first person diagnosed with myelitis turned out to have a previously undiagnosed case of multiple sclerosis. And the second person — well, the circumstances are murky:

The “case narrative” contained in AstraZeneca’s report says the patient had the first dose of the coronavirus vaccine in early June and was fine. She received her second dose in late August. 

On September 2, while running, the study participant “had a trip (not fall) with a jolt.” The report notes that she did not have any obvious injury to her cervical spine.  

The next day, the report says, she had symptoms including difficulty walking, pain and weakness in her arms, pain and reduced sensation in her torso, a headache and reduced ability to use her hands.

Could it be that her fall, not the vaccine, caused the symptoms she temporarily experienced? She was hospitalized on September 5 but was feeling better within a few days. According to the Times, AstraZeneca said it hadn’t confirmed a diagnosis in her case — but CNN says that it’s seen an internal report from AZ that *did* find the woman had “confirmed” transverse myelitis.

Experts in the U.S. would reeeeeally like more information, not just about the second patient but about the one diagnosed with MS. “The highest levels of NIH are very concerned,” said one doctor at the agency to Kaiser Health News. Public faith in the integrity of a COVID vaccine is already shaky, partly because of baseline anti-vax-ism among the U.S. population, partly because no one trusts Trump to prioritize vaccine safety over his electoral interests, and partly because the international competition among manufacturers to produce the “winning” vaccine gives them an incentive to cut corners. Now suddenly we have the manufacturer of the western world’s most advanced vaccine candidate being tight-lipped about two highly alarming cases of possible side effects.

The NIH has yet to get tissue or blood samples from the British patient, and its investigation is “in the planning stages,” Nath said. U.S. scientists could look at samples from other vaccinated patients to see whether any of the antibodies they generated in response to the coronavirus also attack brain or spinal cord tissue…

Neurologists who study illnesses like transverse myelitis say they are rare — occurring at a rate of perhaps 1 in 250,000 people — and strike most often as a result of the body’s immune response to a virus. Less frequently, such episodes have also been linked to vaccines…

More worrisome is a phenomenon called “molecular mimicry.” In such cases, some small piece of the vaccine may be similar to tissue in the brain or spinal cord, resulting in an immune attack on that tissue in response to a vaccine component.

“If there are two cases, then this starts to look like a dangerous pattern,” said one expert to the Times. “If a third case of neurological disease pops up in the vaccine group, then this vaccine may be done.” It should be noted that a British regulatory body agreed with AstraZeneca that the second patient’s myelitis probably wasn’t caused by the vaccine, but neither that body nor AZ itself provided an explanation when they agreed to resume the UK trial. AstraZeneca didn’t promptly notify the public of the two subjects’ neurological problems either — the myelitis diagnoses were leaked — nor did it quickly inform the FDA after it decided to pause the trial to investigate further. It still hasn’t explained how it arrived at the conclusion that the first patient’s myelitis was caused by MS. One expert who spoke to the Times said he found the speed with which the trial resumed “a little disturbing.” Another called AZ’s lack of candor “horrible and unacceptable.”

If you’re looking for a sinister explanation here, you might wonder if the glory to have a British vaccine win the global COVID race is leading British regulators to take a too-rosy view of suspicious medical problems arising in AstraZeneca’s UK trial.

And if that’s not depressing enough, the NYT points out that a side effect caused by Oxford’s vaccine might not be unique to that vaccine. There are other companies out there working with adenoviruses and incorporating bits of SARS-CoV-2 DNA in their vaccine candidates, as Oxford is. If in fact myelitis is being caused by something specific to those “ingredients,” every adenovirus-based vaccine might be a bust on grounds that it’s too risky.

The U.S. arm of AstraZeneca’s trial is still on hold for now while the NIH waits for more info. Within the past few days, in the interest of greater transparency and building public confidence, AstraZeneca, Pfizer, and Moderna have all released their vaccine protocols, i.e. how they’re planning to measure whether their product is effective or not. There’s already criticism of their methods, though, with one doctor complaining to the Times that each company is planning to count mild cases of COVID in determining how well their vaccine works — which means we may not have ironclad data on how well it works in more severe cases, specifically. Stay tuned.