Ireland, Norway, Denmark, Germany, Italy, France... What do UK experts think about the suspension of AstraZeneca in more and more European countries following reports of blood clotting events?

First published in March 2021.

Health officials from the UN and the European Union will meet this week on the AstraZeneca COVID-19 vaccine after several more countries suspended its use, the head of the World Health Organization (WHO) said on Monday.

Agency chief Tedros Adhanom Ghebreyesus told journalists that WHO’s Advisory Committee on Vaccine Safety has been reviewing available data on the vaccine and will meet with the European Medicines Agency (EMA) on Tuesday.

Germany, France, Italy, and Spain have become the latest countries to temporarily halt use of the shot, following reports of blood clots in people who received the vaccine from two batches produced in Europe.

This does not necessarily mean these events are linked to vaccination, but it’s routine practice to investigate them, and it shows that the surveillance system works and that effective controls are in place”, Tedros said.

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Dr. Mariângela Simão, a WHO Assistant Secretary-General, said the agency is working very closely with the EMA, and with national regulatory authorities in Europe and other regions, in assessing the adverse effects of the AstraZeneca vaccine and all other vaccines.

WHO has not received reports about “thrombo-embolic events” in other parts of the world, she added.

Tedros stressed that “the greatest threat” most countries face now is lack of access to vaccines, saying he receives calls from leaders worldwide “almost every day” asking when their nations will receive doses through the COVAX initiative.

What the experts say.

  • Dr Peter English, Retired Consultant in Communicable Disease Control, Former Editor of Vaccines in Practice Magazine, Immediate past Chair of the BMA Public Health Medicine Committee:

“When a vaccine is administered to millions of people, it is inevitable that some adverse events – that would have happened anyway – will happen shortly after vaccination. When deciding whether the events are a coincidence, or caused by the vaccine, you have to consider biological plausibility and whether there are more events than you would expect without vaccination.

“Authorities in various countries have carefully considered the evidence, and concluded that there is no excess of clotting events in people who have been vaccinated – even with the increased awareness of the possibility of such events (and the increased likelihood of reporting them if they should occur that inevitably follows such increases in awareness.)

“It is most regrettable that countries have stopped vaccination on such “precautionary” grounds: it risks doing real harm to the goal of vaccinating enough people to slow the spread of the virus, and to end the pandemic.”

Covid-19 AstraZeneca vaccine. | Flickr/gencat cat

“Vaccine safety is critically important. Our UK regulator, the MHRA, review all reports of adverse events for both vaccines as they are reported. There have been more than 11 million doses of the Oxford-AZ vaccine administered in the UK and no excess reports of deaths or blood clots amongst those receiving the vaccine, compared with the expected rate in the population. The public should have confidence that both vaccines used in the UK vaccination programme are safe and highly effective at preventing severe disease, including blood clots and deaths caused by Covid.”

“The report from the Paul Ehrlich Institute gives a diagnosis for recent reports of adverse events following administration of the Oxford AtraZeneca vaccine, Cerebral Venous Sinus Thrombosis (CVT). In the briefing it was stated that seven cases have been identified in 1.6 million vaccinated (about 4.5/million post vaccination).

“While it has been reported that background incidence of CVT is only 2 to 5 cases per million per year and was considered to be very rare, more recent papers have suggested it is more common than previously thought. A study from Australia found  15.7 cases per million per year and one from the Netherlands 13.2 cases per million per year. The reported incidence was actually higher in people under 50 than in people over 50 years old. So the estimated background incidence of is only 2 to 5 cases per million per year would appear to be underestimated by about 4 to 8 fold.

“So we would normally expect to see about 1 or 2 cases per month per million people in people under 50. So it does appear that CVT has been reported more commonly than expected at least in Europe. However, one of the key problems with identifying association between rare/uncommon events is that it is not just one type of possible event that is being looked for.

Clearly this possible association needs to be thoroughly investigated, but we do need to consider the real harm from delays in immunization campaigns at a time when the incidence of COVID is still increasing in several European counties when deciding whether or not to pause vaccination campaigns.”

“The news that Germany and other countries have suspended roll out of the AZ vaccine is disappointing. Whilst it is right that any possible links between serious adverse reactions to a vaccines are investigated, it is important to establish the likelihood of causation, as opposed to association, when doing so. The numbers of clotting events associated with the vaccine are very small, and according to the figures from AZ are well below the average that you might expect in any given population – we must remember that many millions of people have been safely vaccinated. Moreover, it is likely that the early stages of the European rollout have primarily comprised elderly and more clinically vulnerable patients, which might be expected to have a much higher incidence of random clotting-related events.

“Thus, the concerns raised in my view, whilst valid and worthy of investigation, are probably not proportionate to the response in terms of halting mass vaccination in multiple countries. Since many European countries are currently experiencing another resurgence of SARS-CoV2 infections and yet are lagging behind in terms of roll out, the importance of continuing the vaccination programmes cannot be underestimated, and the harm caused by depriving people of access to a vaccine will likely vastly outweigh even the worst case scenario if any link to the clotting disorders is eventually found. It should also be noted that nationwide gestures such as this are bound to fuel hesitancy, or more extreme anti-vaccine sentiment, further undermining the vaccination effort.”

“It would seem the move has been done following reports of serious blood clotting events in adults in Norway.

“These events were said by the Norwegian Institute responsible for delivering vaccines to be “they have had a reduced number of blood platelets. Blood clots and subsequent brain haemorrhages are a rare condition.”

“However, what these authorities do not make clear is that these coagulation disorders are very common in patients with Covid-19. Unless we are sure that those who suffered these unfortunate events very definitely did not have COVID-19 then it would seem to be premature to suggest it was the vaccine that caused these events.

“It has been well known for over a year that coagulation disorders, both clotting causing strokes, and bleeding (thrombocytopenia, which is a reduced number of platelets in the blood), are very common in patients with COVID-19. Early reports from China noted over 30% of patients reaching hospital had thrombocytopenia.

“It is also a principle of regulatory action that when action is taken in regard to a particular product, that the alternatives definitely do not have the same problem. There was a case of thrombocytopenia in the US trial for the Pfizer vaccine, but detailed investigation made it clear that the vaccine was not the cause. The publicly available information on the AstraZeneca vaccine lists a total of 35 cases of thrombocytopenia reported on “Yellow Cards” in the UK up to 8th March 2021. This is a very small proportion of the yellow card reports which total over 54,000 in the context of nearly 10 million vaccinations delivered. For the Pfizer vaccine there are a total of 22 reports of thrombocytopenia out of 33,000 reports and well over 10 million vaccination doses. It is clear that the proportion of reports for this bleeding disorder is not different in the two vaccines.

“It is entirely reasonable that detailed studies are done on the vaccines in regard to coagulation disorders, but it seems a step too far in taking precautions that would stop people getting vaccines that would prevent disease.” 

Going Further:

  • The following European countries have now totally suspended the use of AstraZeneca for vaccination: Denmark, France, Germany, Iceland, Italy, Ireland, Norway, Slovania, Spain, and The Netherlands.
  • The following European countries only suspended vaccination from a same batch named ABV5300: Austria, Estonia, Latvia, Lithuania, Luxembourg, and Romania.
  • Coronavirus Yellow Card reporting site | MHRA

PMP News reporting

[This piece was originally published in PMP Magazine on 15 March 2021.]

(Cover: Flickr/Marco Verch Professional Photographer. / Licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.)

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