AstraZeneca COVID vaccine temporarily banned in growing list of countries. Here’s why

Out of an abundance of caution, Germany, France and Italy issued temporary bans on the use of AstraZeneca’s two-dose COVID-19 vaccine on Monday following reports of some people developing blood clots shortly after vaccination.

A handful of people have died after receiving the shot, which is not yet authorized for emergency use in the U.S.; it’s unclear if the reported blood conditions caused their deaths.

These countries join at least a dozen others in recent weeks that either partially or temporarily suspended use of the shot, despite a lack of evidence that the vaccine was responsible for the rare events.

So far, Norway, Iceland, Bulgaria, Estonia, Latvia, Denmark, Austria, Ireland, the Netherlands, Lithuania, Luxembourg, as well as Congo in Central Africa and Thailand in Asia have stalled their rollouts of the AstraZeneca coronavirus vaccine, several media outlets reported.

However, top health officials still support the use of the vaccine, including the World Health Organization and the European Medicines Agency (EMA), both of which say there’s no available evidence that suggest the vaccine caused the conditions that may have took the lives of at least two people in Italy and one person in Denmark.

“The vaccine’s benefits continue to outweigh its risks and the vaccine can continue to be administered while investigation of cases of thromboembolic events is ongoing,” the EMA said in a statement Thursday.

The agency said there have been 30 cases of thromboembolic events (formation of blood clots) among the nearly 5 million people vaccinated with the AstraZeneca vaccine as of March 10. That number is “no higher than the number seen in the general population,” the agency said, meaning the medical conditions reported in vaccinated people are expected to occur randomly in a group so large.

AstraZeneca shared the same reasoning in a statement posted Sunday.

“Around 17 million people in the EU and UK have now received our vaccine, and the number of cases of blood clots reported in this group is lower than the hundreds of cases that would be expected among the general population,” said Ann Taylor, AstraZeneca’s chief medical officer. “The nature of the pandemic has led to increased attention in individual cases and we are going beyond the standard practices for safety monitoring of licensed medicines in reporting vaccine events, to ensure public safety.”

The company said a review of the millions of vaccinated individuals in the region reveals no evidence of increased risks for blood clots in the lungs or veins, or for thrombocytopenia — a condition that lowers blood platelets — in any age group, gender or batch of vaccines.

There was also no evidence of increased bleeding in the more than 60,000 participants in AstraZeneca’s clinical trial.

“Additional testing has, and is, being conducted by ourselves and independently by European health authorities and none of these re-tests have shown cause for concern,” the company said. “The safety of the public will always come first. The Company is keeping this issue under close review but available evidence does not confirm that the vaccine is the cause. To overcome the pandemic, it is important that people get vaccinated when invited to do so.”

What to know about the AstraZeneca COVID-19 vaccine

The World Health Organization granted AstraZeneca’s coronavirus vaccine emergency use for adults in more than 50 countries on February 15. The shot requires two doses separated by about four to 12 weeks.

Late-stage clinical trials in the U.K, Brazil and South Africa, where more contagious coronavirus variants have emerged, showed the vaccine had an efficacy rate of 82% against symptomatic coronavirus infection after two doses were given about 12 weeks apart.

It also prevented severe cases of COVID-19, the disease the virus causes, and hospitalizations after 22 days following the first dose.

Unlike the Pfizer and Moderna COVID-19 vaccines authorized in the U.S., the AstraZeneca shot works by delivering a harmless version of a chimpanzee virus called an adenovirus that has been genetically modified so it cannot make copies of itself in humans or cause disease.

The manipulated virus contains instructions on how to make the spike protein the novel coronavirus uses to enter human cells. So, when a vaccinated person comes into contact with another infected individual, their immune system is already primed to recognize the coronavirus and attack it.

The pharmaceutical company developed the vaccine with the University of Oxford.

Results from the company’s 30,000-person clinical trial in the U.S. are “currently being reviewed by independent monitors to determine whether the shot is safe and effective,” Reuters reported Monday.

Director of the National Institutes of Health Dr. Francis Collins told the outlet that if the data prove positive, the vaccine could be granted emergency use in the U.S. in about a month, becoming the fourth COVID-19 shot in the nation.