France, Germany, Spain and Italy joined several other European nations in temporarily suspending the use of the Oxford-AstraZeneca Covid-19 vaccine on Monday, due to concerns that the injections may be related to an increased risk of blood clots . But experts say no causal link has been identified so far and warned that the suspensions could end up doing more harm than good.
An increasing number of European countries have chosen to stop the vaccine’s launch after reports that a small number of patients developed blood clots after receiving at least one dose.
The World Health Organization said Monday that “there is no evidence that the incidents are caused by the vaccine”, and advised that vaccination campaigns should continue as long as concerns about clotting are investigated. Several experts agreed that, without the burden of further proof, the suspensions could lead to future outbreaks – especially since they are occurring at a precarious time for Europe in the pandemic.
“There is still a lot of Covid in Europe, so given that this is a public health emergency, you would need to see a very strong signal in the data to suspend a vaccine program,” said Michael Head, senior researcher in global health at the University of Southampton, UK. “If we have this scare and there is nothing there, will there be more cases and deaths from Covid-19 because of the delay in launching the vaccine? Will this increase the hesitation of the vaccine? ”
Head said that while any potential side effects of the vaccine must be investigated thoroughly, decisions to stop vaccination campaigns need to strike a delicate balance between risks and benefits. At the moment, he said, there is no data to suggest that AstraZeneca vaccines are linked to blood clots.
“I can’t see a signal strong enough to justify withdrawing the vaccine from national launches,” said Head. “Considering that there is still a lot of Covid in Europe and the emergence of the situation, I am not sure why vaccine programs are being suspended.”
Blood clots are dangerous because they can clog blood vessels and cause breathing problems, heart attacks and strokes. Blood clots can cause damage to organs like the heart and brain and, depending on their size and location, can be deadly.
Germany’s health minister, Jens Spahn, said on Monday that the decision to stop the AstraZeneca vaccine came from the Paul Ehrlich Institute, the country’s vaccine regulator, and was based on new reports of vaccine-related blood clots in Germany and in Europe. The institute recommended further study of seven cases of thrombosis, or blood clots, in the brain that have been detected in people who have been vaccinated. In Germany, 1.6 million people received the AstraZeneca vaccine.
Spahn said the decision to stop using the vaccine was “purely preventive”.
Denmark was the first country to halt the launch of the AstraZeneca campaign last week, after a person developed multiple clots and died 10 days after receiving at least one dose of the vaccine.
Since then, several other countries have added their own suspensions, including Norway, Iceland, the Netherlands, the Democratic Republic of Congo and Indonesia.
The European Medicines Agency, the continent’s main drug regulator, said Monday that a “rigorous analysis of all data” is underway, but added that the reported cases of blood clots in vaccinated people “do not appear to be greater than that observed in the general population. “
One serious type of clotting event cited by the German health ministry was cerebral vein thrombosis, a rare stroke caused by blood clots in the brain. Cerebral vein thrombosis affects five people in 1 million each year, according to Johns Hopkins University. In the United States, up to 100,000 people die each year from blood clots, such as deep vein thrombosis and pulmonary embolism, according to the Centers for Disease Control and Prevention.
The agency also highlighted the important role that the vaccine plays in preventing serious illnesses caused by Covid-19.
“While its investigation is ongoing, EMA currently maintains the view that the benefits of the AstraZeneca vaccine in preventing Covid-19, with its associated risk of hospitalization and death, outweigh the risks of side effects,” said agency officials in an announcement.
The European Medicines Agency said it would meet on Thursday to assess the results of its investigation and decide whether further action is needed.
In a statement released on Sunday, AstraZeneca said there is no indication in the company’s safety data that the vaccine is associated with an increased risk of blood clots. The drugmaker said there were 37 reported cases of blood clots in more than 17 million people vaccinated in the European Union and the United Kingdom. Fifteen of the reported cases were of deep vein thrombosis and 22 pulmonary embolisms, according to AstraZeneca.
“This is much smaller than would be expected to occur naturally in a general population of this size and is similar in other licensed COVID-19 vaccines,” said the company in its statement.
Stephen Evans, professor of pharmacoepidemiology at the London School of Hygiene & Tropical Medicine, said that with so many doses of the AstraZeneca vaccine already administered, scientists should be able to see signs of rare side effects, if they are occurring. In the United Kingdom, for example, about 11 million doses of the AstraZeneca vaccine have been administered, out of the 20 million people vaccinated in the country.
“With the number of people vaccinated in the UK, we will be able to detect rare things – on the order of 1 in 100,000 people,” he said.
Evans said the suspensions appear premature, especially without more information about incidents of blood clotting disorders. Blood clots are, for example, a complication of Covid-19, he said.
“We need to make sure that these cases did not occur in people with undiagnosed Covid, because people with Covid-19 are at increased risk for thrombosis,” said Evans.
And while safety should be paramount, Evans said that one consequence of stopping the launch of a vaccine before adequate data is available is that it can contribute to the vaccine’s hesitation.
“I think it will undermine confidence in the AstraZeneca vaccine, whether guaranteed or not,” said Evans. “And that will undermine confidence in Covid’s vaccines in general and in the vaccines themselves in general.”
Head was also concerned about the effect these actions could have on vaccination initiatives across Europe, adding that all the information that has been made publicly available so far does not justify suspending the use of the vaccine.
“It’s a little worrying,” he said, “and it can do more damage than stop.”