AstraZeneca’s Vaccine Faces Blood Clot Considerations


Germany, France, Italy and Spain have all canceled AstraZeneca’s COVID-19 vaccine after reports of rare blood clots in people given the vaccines.

These moves by the four largest countries in the European Union follow pauses in several smaller member states – and mark a new crisis of confidence for an affordable vaccine that is seen as the best hope of accelerating COVID-19 vaccination in developing countries.

Experts point out that there is still no clear evidence that the vaccine is causing these reported clots and that the cases are being investigated by regulators. However, the recent concerns follow earlier questions from scientists about how the company communicated issues with the safety and effectiveness of its vaccine. It also comes right before AstraZeneca is expected to release results from a large-scale clinical trial to determine whether the FDA has approved the vaccine for use in the United States.

The vaccination breaks in Europe were triggered by reports of three hospital stays, including a deceased patient among people given the vaccine in Norway and another death in Denmark. In a statement released on March 11, the European Medicines Agency – the regulator equivalent to the FDA in the EU – said there had been a total of 30 cases of “thromboembolic events” or blood clots among the 5 million people received AstraZeneca- Recordings in the EU.

“There is currently no evidence that vaccination caused these conditions that are not listed as side effects with this vaccine,” the EMA said. “The position of the EMA Safety Committee is that the benefits of the vaccine continue to outweigh the risks and that the vaccine can still be administered.”

AstraZeneca said that a total of 37 cases of pulmonary embolism and deep vein thrombosis were reported, both conditions caused by blood clotting, which is less than would be expected based on the rate in the general population.

“Around 17 million people in the EU and the UK have now received our vaccine, and the number of blood clot cases reported in this group is fewer than the hundreds that would be expected,” said Ann Taylor, chief medical officer of the Company issued a statement dated March 14.

And the World Health Organization is urging countries to keep using the vaccine, reiterating that there is no evidence that it causes blood clots. WHO experts will meet on Tuesday to discuss blood clot reports.

However, a handful of incidents halted some countries. According to Federal Health Minister Jens Spahn, seven cases of a rare disease, cerebral venous sinus thrombosis (CVST), were reported by 1.6 million people in Germany who were given the AstraZeneca vaccine. The Paul Ehrlich Institute, part of Germany’s health ministry, said Monday it was concerned the condition was being reported alongside unusual bleeding and a low number of platelets that form blood clots and prevent bleeding.

The few cases that have occurred in Germany so far would be more than expected, but could be a statistical coincidence. “[T]The likelihood of such a statistical clustering for a result is actually quite high, even if there is no cause and effect, ”said Paul Hunter, public health specialist at the University of East Anglia, in a comment distributed through the UK Science Media Center has been.

The EMA meets on Tuesday to discuss blood clotting concerns and is expected to release its conclusions on Thursday. A longer vaccination break would be worrying as COVID-19 cases are rising again in several EU countries – with Italy recording a particularly alarming increase – as more contagious variants spread.

Experts contacted by BuzzFeed News said that without knowing more about the patients’ cases, there wasn’t enough evidence to draw firm conclusions about whether the vaccine caused clotting. “We want to know the age of the cases, their history, and the conditions that could predispose their risk to a blood clot or bleeding,” said Orly Vardeny of the University of Minnesota, a pharmacist specializing in heart health.

“It may or may not be vaccine-related. If it’s a vaccine, and if it’s not everywhere, the most likely explanation is a problem with the production batch, ”said John Moore, a virologist at Weill Cornell Medical College in New York who works on vaccine development BuzzFeed News. (Some countries, including Austria, have specifically stopped vaccination against certain lots of the AstraZeneca vaccine.)

The new concerns are the latest in a string of stumbling blocks over AstraZeneca’s COVID-19 vaccine developed at Oxford University. Back in November, AstraZeneca claimed in a press release that its vaccine was 70% effective overall and could be up to 90% effective when given in half a dose for the first of two shots. However, many scientists were skeptical, especially after the drug company admitted that this regimen was the result of a dosage miscalculation. AstraZeneca later added to the confusion by changing its explanation for claiming 90% effectiveness from the dosage itself to the delay between the two doses.

A more serious blow came in February when studies in South Africa showed the vaccine was ineffective against the more contagious variant of the coronavirus circulating there. South Africa abruptly stopped plans to use AstraZeneca’s vaccine and instead switched to vaccines from Johnson & Johnson and Pfizer / BioNTech.

Now scientists are waiting for the results of a large study of the AstraZeneca vaccine that has been carried out in the US and other countries. This will be the cornerstone of the company’s filing to get the vaccine approved for use by the FDA. However, some experts wonder if the addition of AstraZenecas to the armory of vaccines used in the US will create further problems, as anti-Vaxxers are likely to use the negative public to undermine the wider vaccination campaign.

“Does it really have a niche to fill? Would it be trustworthy enough? Or will it be just another headache? “said Moore.

Children’s Health Defense, an organization that has been spreading misinformation and conspiracy theories about vaccines for years, has already highlighted news that several European countries are stopping use of the vaccine.

Where the vaccine could make a big difference is in developing countries, especially Africa, where vaccine adoption is far behind. The Biden Administration is already under pressure to donate manufactured doses of the AstraZeneca vaccine to poorer nations, the New York Times reported on March 11. Meanwhile, COVAX – the collaboration between WHO, the Coalition for Innovation to Prepare for Epidemics, and Gavi The Vaccine Alliance, which aims to provide affordable vaccines to poorer countries, is relying on AstraZeneca’s vaccine to deliver hundreds of millions of doses in developing countries.

“Safety is our primary concern: we know that national authorities and WHO are closely monitoring the situation and that the COVAX facility will follow their instructions and recommendations,” a Gavi spokesperson responded to inquiries from BuzzFeed News. “At present, no causal link has been established between the vaccine and thromboembolic events in individuals, and the vaccine remains an important and powerful public health tool in the fight against this pandemic.”