Canadian officials and experts have sought to assure the vaccine is safe, after several countries paused its use.
The European Union’s medicines regulator has said the benefits of using the AstraZeneca vaccine against COVID-19 still outweigh the risks of side effects, as a growing number of mostly European countries have halted the use of the jab amid a few fatal cases of blood clotting.
Speaking during a news briefing on Tuesday, Emer Cooke, head of the European Medicines Agency (EMA), said the body was investigating all the available data and clinical circumstances of each case to deliver a conclusion on Thursday afternoon.
Despite the probe not being completed, Cooke stressed the EMA is “firmly convinced that the AstraZeneca vaccine, in preventing COVID-19 with its associated risk of hospitalisations and deaths, outweighs the risks of side effects”.
The World Health Organization (WHO) aligned last week with the EU regulator position saying there was no evidence the vaccine carries an increased risk of blood clots.
Cooke also noted that thousands of people across the EU develop thromboses every year for a variety of reasons and that there were no reports of increased blood clots in the clinical studies of the vaccine developed by AstraZeneca with the University of Oxford.
Still, experts would undertake a “very rigorous analysis”, she said.
More than 16 countries – including Germany, Italy, France and Spain – have suspended the use of the jab after about 37 reports of blood clots and at least five deaths among people who had received the shot.
Some scientists caution that such a figure is lower than what would occur naturally in a general population, considering that the AstraZeneca vaccine has been administered to more than 17 million people in the EU and Britain.
“The evidence is that AstraZeneca vaccine has been given to millions … and we have found that there is no link with the development of blood clots in excess of what normally happens,” Bharat Pankhania, senior lecturer at the University of Exeter College of Medicine, told Al Jazeera.
“It is rather a coincidence rather than a link,” he added.
Europe has the luxury to be able to pick from several vaccine candidates — but the decision is still not an easy one on the continent, where the virus is again surging and where the vaccination campaign has repeatedly stumbled.
In the past week, COVID-19 infections have begun to rise steadily, from 200 per million in mid-February to 270 per million last weekend. That level is still a long way off from the EU record of 490 per million in November, but a worrying trend nonetheless.
Many countries have placed their bets on the AstraZeneca vaccine which is cheaper and easier to handle than some other shots. The jab has so far played a huge role in the global initiative to ensure vaccines get to poorer countries, known as COVAX.
However, the WHO reiterated on Friday that the AstraZeneca batches now under scrutiny were manufactured in Europe, while the drugmaker’s vaccines destined to COVAX were being produced by manufacturers in India and South Korea.
The difficulty of choosing weather to halt the vaccine rollout was clear in Thailand, the first country outside Europe to temporarily suspend the use of the AstraZeneca vaccine, only to recant on Tuesday — when its prime minister received a dose.
“There are people who have concerns,” Prayuth Chan-ocha said after getting the shot. “But we must believe doctors, believe in our medical professionals.”
Many other countries in Asia have likewise shrugged off concerns, though Indonesia halted the use of the shot this week, saying it would wait for a WHO report on the issue.