LONDON (AP) -- The world is awaiting a decision from Europe's top medical regulator on its investigation into whether there is any evidence to show the AstraZeneca coronavirus vaccine is linked to a small number of blood clots reported in people across the continent.
The European Medicines Agency's expert committee is set to announce the results of its investigation later Thursday.
Earlier this week, more than a dozen countries including Germany, France, Spain and Italy suspended immunization using the AstraZeneca COVID-19 vaccine after reports of unusual blood clots in several people among the 17 million who have received at least one dose in Europe. Both the EMA and the World Health Organization have said there is no current evidence to suggest the vaccine was responsible and that the benefits of immunization far outweighed the potentially small risk of getting vaccinated. AstraZeneca said after a careful review of its COVID-19 immunization data, it found no evidence of any increased risk of blood clots in any age group or gender in any country.
On Tuesday, EMA executive director Emer Cooke said the agency's priority was the the vaccine's safety and that it would consider issues including if extra warnings needed to be added for the AstraZeneca vaccine. She noted the daily toll COVID-19 is continuing to take across the continent and said vaccines were critical to stopping its spread.
"We are worried that there may be an effect on the trust of the vaccines," she said. "But our job is to make sure that the products that we authorize are safe and we can be trusted by the European citizens."
The pause in vaccination using the AstraZeneca shot comes as COVID-19 is surging across the continent and as Britain is expecting major delays in its vaccine deliveries. Tens of thousands of new daily cases have prompted new lockdown measures in Italy, caused hospitalizations in France to spike and led German officials to announce that a third wave of COVID-19 has begun.
Figures from the European Centers for Disease Prevention and Control this week show there are about 7 million unused AstraZeneca vaccines across the 27-nation EU.
The German government defended its decision to suspend the use of the AstraZeneca vaccine, saying it was based on expert advice.
Government spokeswoman Ulrike Demmer told reporters in Berlin on Wednesday that while she understood some might be worried by the move it should be seen as a sign that "trust in our control mechanisms is justified."
"That's why this step could also strengthen trust" in the vaccines, she said. "Concerns are taken seriously and examined. And as soon as these concerns are cleared up, a vaccine can be used again without hesitation."
Germany would rely on the EMA decision for how to proceed, Health Ministry spokesman Hanno Kautz said.
"It's clear that the EMA decision is binding and of course we will follow the EMA decision too," Kautz said.
Any time vaccines are rolled out widely, scientists expect some serious health issues and deaths to be reported, simply because tens of millions of people are receiving the shots. Determining whether or not the vaccine is to blame can be difficult, since most of the people getting inoculated first are those most at risk of the coronavirus.
But because there are no long-term data on any of the COVID-19 vaccines, any potential signal of trouble must be thoroughly investigated.
Because clinical trials are only done in tens of thousands of people, extremely rare side effects often aren't detected until vaccines are used in many millions of people, long after they have been licensed. For example, it took nearly a year after vaccination campaigns began following the 2009 swine flu pandemic for European officials to notice an increase of narcolepsy in children and teenagers who got the GlaxoSmithKline vaccine.
And in the Philippines, the government in 2017 was forced to stop its national dengue vaccination program with a new shot developed by Sanofi Pasteur after about a year, when more than 130 children who were immunized died. It turned out the vaccine worsened the effects of dengue in any children who hadn't been previously infected.
"It's right to investigate any potential signals of problems, but you can do that while you continue immunization," said Michael Head, a senior research fellow in global health at the University of Southampton. "The millions of doses being administered means we will see coincidental clusters of conditions," he said. "If we pause the vaccine rollout every time there's a possible signal, it won't be much of a rollout."