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The participant who triggered a global shutdown of AstraZeneca’s Phase 3 Covid-19 vaccine trials was a woman in the United Kingdom who experienced neurological symptoms consistent with a rare but serious spinal inflammatory disorder called transverse myelitis, the drug maker’s chief executive, Pascal Soriot, said during a private conference call with investors on Wednesday morning.

The woman’s diagnosis has not been confirmed yet, but she is improving and will likely be discharged from the hospital as early as Wednesday, Soriot said.

The board tasked with overseeing the data and safety components of the AstraZeneca clinical trials confirmed that the participant was injected with the company’s Covid-19 vaccine and not a placebo, Soriot said on the conference call, which was set up by the investment bank J.P. Morgan.


Soriot also confirmed that the clinical trial was halted once previously in July after a participant experienced neurological symptoms. Upon further examination, that participant was diagnosed with multiple sclerosis, deemed to be unrelated to the Covid-19 vaccine treatment, he said.

The new disclosures made by Soriot were heard by three investors participating on the call and were shared with STAT. An AstraZeneca spokesperson did not respond to an email request for further comment.


One investor on the call said Soriot’s comments were intended to reassure investors that the company was taking the possible vaccine safety event seriously, and to reverse any damage to the company’s stock price. “A vaccine that nobody wants to take is not very useful,” said Soriot.

To date, AstraZeneca’s public statements on the pause have been sparse with details. For instance, the company has not publicly confirmed that this is the second time its trials have been stopped to investigate health events among participants.

On Wednesday, the company issued a statement, attributed to Soriot, saying AstraZeneca would be guided by a committee of independent experts in determining when to lift the hold on the trial “so that we can continue our work at the earliest opportunity to provide this vaccine broadly, equitably and at no profit during this pandemic.”

AstraZeneca’s is the first Phase 3 Covid-19 vaccine trial known to have been put on hold. Such holds are not uncommon, and it’s not clear yet how long AstraZeneca’s will last.

“To have a clinical hold, as has been placed on AstraZeneca as of yesterday, because of a single serious adverse event is not at all unprecedented,” Francis Collins, the director of the National Institutes of Health, told a Senate panel on Wednesday. “This certainly happens in any large-scale trial where you have tens of thousands of people invested in taking part, some of them may get ill and you always have to try to figure out: Is that because of the vaccine, or were they going to get that illness anyway?”

AstraZeneca only began its Phase 3 trial in the U.S. in late August. The U.S. trial is currently taking place at 62 sites across the country, according to, a government registry, though some have not yet started enrolling participants. The Phase 3 trial in the U.S. aims to enroll about 30,000 participants at 80 sites across the country, according to a release last week from the NIH. Phase 2/3 trials were previously started in the U.K., Brazil, and South Africa.

The vaccine — known as AZD1222 — uses an adenovirus that carries a gene for one of the proteins in SARS-CoV-2, the virus that causes Covid-19. The adenovirus is designed to induce the immune system to generate a protective response against SARS-2. The platform has not been used in an approved vaccine, but has been tested in experimental vaccines against other viruses, including the Ebola virus.

Transverse myelitis is a serious condition involving inflammation of the spinal cord that can cause muscle weakness, paralysis, pain and bladder problems. In rare instances, vaccines have triggered cases of transverse myelitis; although it can also be caused by viral infections.

Helen Branswell and Lev Facher contributed reporting. 

  • Thank you for this very informative and enlightening article!
    Why are President Trump and VP Pence so intent on pushing a vaccine on the American population through operation warp speed, when the huge white elephant in the room, (which is seemingly being ignored by them, along with conservative pro American media, as well as the progressive msm), which is: The vast majority of us freedom loving Americans do not want anything to do with a vaccine! We don’t want it!
    To hear media reporters talk about it, and President Trump as well-one would get the impression that we are all like bleating sheep, and mooing cows, and eager puppies feverishly and anxiously awaiting the miracle vaccine that will save us from this dreaded virus 🤔
    I am a passionate supporter of our great President, but every time I hear him talk, he mentions getting this vaccine going by November
    It has me greatly concerned!
    On top of it, you have Kamala Harris speaking about being against the vaccine if it’s promoted by President Trump!
    I do not agree with anything she says or stands for, but this is one issue that has given me pause…not that I intend on voting for the Biden-Harris ticket
    However this vaccine issue is sure to lose a lot of on the fence possible supporters/voters for Trump in November-because like myself they do not want to be forcibly vaxxed-esp against their will.
    Jobs or no jobs, good economy or not, it boils down to tyranny-a concept we all thought our President was against

    • I agree. Vaccines for Democrats since they are the ones promoting lockdowns and saying we can not end the lockdowns until there is a vaccine, which, of course, is music to the ears of pharma company executives. However, I don’t think I’ll be taking any HCl – gives me heartburn, but how about maybe HCQ (hydroxychloroquine or even ivermectin) + Zn instead. But here is another protocol: an ionophore (like HCQ such as EGCG -green tea, quercetin -onions and apples, honokitiol – western red cedar essential oil, or even pyrithione ) + zinc – beef liver and pumpkin seeds)+ Vit D3 – sunshine+ Vit C -fruit) + Vit A -greens in a salad. beef liver + Vit K2 – grass fed butter and beef liver, Vit E – sunflower seeds + iodine (kelp) + beta-glucan (oats and/or mushrooms, and selenium (3 Brazil nuts a day) – all immune boosters with antiviral properties. A Chinese study of 300 people who died from Covid-19 found that all were Vit D3 deficient. How about achieving a normal weight. Being obese increases one’s risk of a severe Covid-19 illness and death by 300% or more if one does develop a Covid-19 illness. A small clinical trial run in China with HCQ pitted against ivermectin found ivermectin to be marginally better than HCQ (100% effective vs 96%). Vitamin C help preserve the thymus gland as one ages – the thymus gland is the storage gland for one’s memory T cells. About 20% of the population has some antibodies to the SARS-CoV-2 virus because of previous corona virus infections since about 20-30% of colds are caused by a corona virus and there is some cross immunity to different corona viruses.

  • It would be nice to know if the participant who was diagnosed with multiple sclerosis (MS)in July had received the COVID-19 vaccine or the placebo. I don’t know how many people had received the vaccine in July compared to today, but the yearly incidence of MS in the US is about 30 cases per million. If you work out the numbers on the case of transverse myelitis (TV), it’s hard to understand the logic of allowing the trial to continue.

    If 18,000 participants received study drug in the trial, presumably that means that 9,000 received the “active” vaccine and not placebo. One participant being diagnosed with transverse myelitis implies a frequency of 1 case per 9,000, or 111 cases per million.

    According to the US National Multiple Sclerosis Society, the annual incidence of TV is 1.34 to 4.60 cases per million, or 1.2% to 4.1% of the implied incidence rate in this trial so far, with 60% of enrollment complete.

    If the MS case occurred in a participant taking the COVID-19 vaccine candidate, and no neurological disease of these autoimmune phenotypes has been observed in participants receiving placebo, it looks unlikely that the vaccine is not related, particularly in the short duration of the trial. Now think about the possibility that this vaccine may be given annually, and that hundreds of millions of people may be dosed before the long-term signals come in based on market use.

  • I have zero fear of this weak virus. It has a 99 % recovery rate for those of us without underlying health conditions under 65. Hard pass on this and all vaccines.I keep my immune system up. I stay healthy and rarely if ever get sick. God didnt send me here broken.

  • so my two cents is why not just increase your intake of zinc and vitamin c, as well as and uptake in garlic and raw honey consumption, far as i can tell those dont cost not even close by a longshot the amount $$$$ the drugs that only serve to make the rich richer and in the case of 2% of population who takes the vaccine, the sick sicker.

    • Pure Baloney you profess and spread. No scientific proof whatsoever and you healthy people with no symptoms continue to infect those of us old and vulnerable people while you put out such BS . How can an old person with diabetes protect themselves with your advice . It’s BS.

    • um, that does not make big pharma any money. I told a friend of mine about vit. D months ago. he never got sick and has been around the illness. mental illness is the pandemic. people who love masks and their hypochondria. that is what this is about…they are lunatics who belong in an asylum.

    • Actually there are two studies that demonstrate a protective effect from Vitamin D, not C, against the COVID 19. Vitamin D improves ones immune system thereby adding some protection to people who contract the virus. It’s not curative but helps. AND there is some science out there to support this from a study in Wuhan and another in Spain. It’s a no brainer as Vitamin D is cheap and safe.

  • I thought the AstraZenica vaccine was really the Oxford developed vaccine and that AstraZenica was only involved in financing, organizing trials, mass manufacturing, and distribution. I thought the Oxford vaccine was the ONLY one that caused the creation of T-cells (in addition to antibodies) that actually seek out the covid19 virus and kill it. The others are messenger RNA TYPE (Moderna, Pfizer) and do NOT produce T-cells. However, based on your reporting, this is NOT the Oxford University developed vaccine but is an AstraZenica developed vaccine. So, either your reporting is shoddy and misrepresents the truth, or the Oxford University vaccine is no longer being worked on.

    • This is how it usually goes. Big Pharma don’t do all the research, they buy molecules that Biotech Companies and Universities develop and test (either in collaboration or by themselves). So Oxford Univ developed the vaccine (usually underpaid post-docs, but I’m not going to go there) and did pre-clinical trials. If they results are successful they present them to a Pharma Company (Astra Zeneca in this case) that buys the product and starts the actual Clinical trials (Phases 1 to 4).
      Ok, just to be clear, no vaccine is producing T cells. What most of them are doing (either with Adenovirus or mRNA) is making the host’s cells (subject injected) to produce a fragment of the virus, then the host T-cells will recognize that as a threat and start the immune reaction that will lead to Antibody (early phase protection, then they get clear out the body) and memory cells (long term protection) production.

      I hope this helps

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