Ireland has temporarily suspended administration of a COVID-19 vaccine made by AstraZeneca following reports of abnormal blood clotting in several people.
The move comes after countries including Italy, Austria, Norway, Denmark, Iceland and Latvia suspended, delayed or limited rollout of the vaccine over safety concerns.
The AstraZeneca vaccine, made in conjunction with the University of Oxford, is not approved in the U.S. But it is used widely in Europe, and about 117,000 doses have been administered in Ireland — mostly to frontline health care workers.
Ireland's department of health made the decision to defer its rollout of the vaccine even though "it has not been concluded that there is any link between the COVID-19 Vaccine AstraZeneca and these cases" of blood clotting, said Dr. Ronan Glynn, the department's deputy chief medical officer, in a statement.
"The decision to temporarily suspend use of the AstraZeneca Covid-19 vaccine was based on new information from Norway that emerged late last night," Stephen Donnelly, Ireland's Health Minister, said in a tweet Sunday. "This is a precautionary step."
Ireland's National Immunisation Advisory Committee recommended deferring the AstraZeneca vaccine after learning of four new "serious blood clotting events" following vaccination among people in Norway.
The Norwegian Medicines Agency reported that several younger vaccinated people experienced bleeding under the skin after getting the shot. In addition, there were four reports of severe blood clots or brain hemorrhage, including one death, in younger people.
Abnormal clotting can produce blood clots that cause strokes, heart attacks and other potentially fatal health events. It can also cause uncontrolled bleeding in the brain and elsewhere.
But experts say it's not clear whether the vaccine can be blamed for any of the clotting problems in people who had been recently vaccinated.
"There are some proportion of people who are going to get blood clots anyway," Dr. Seema Yasmin, an epidemiologist and clinical assistant professor at Stanford, told NPR's Here & Now on Friday. So it makes sense that the European Medicines Agency and the World Health Organization continue to support the vaccine's use, Yasmin said.
"Truly, the benefits outweigh the risks," she said.
The European Medicines Agency is investigating reports of clotting events in people who got the AstraZeneca vaccine. The agency plans to report on its findings within a few days.
In the meantime, both that agency and the WHO continue to support use of the AstraZeneca vaccine.