Ireland suspended use of the COVID-19 vaccine by Oxford-AstraZeneca on Sunday, citing reports of unusual blood clotting problems among people who recently received shots in Norway.

The decision followed a new advisory from Norway on Saturday that four people given the AstraZeneca vaccine had experienced blood clotting issues and all had low platelet counts. Leading public health agencies, including the World Health Organization, point out that millions of people have received the vaccine without experiencing such blood clotting issues, and that experts have not found a causative link between any of the vaccines and the conditions.

“The decision to temporarily suspend use of the AstraZeneca COVID-19 vaccine was based on new information from Norway that emerged late last night,” Ireland’s health minister, Stephen Donnelly, said on Twitter. “This is a precautionary step.”

Regulators like the European Medicines Agency are investigating to determine whether there is any evidence of any link.

AstraZeneca defended its vaccine Sunday, saying that the company is continually monitoring its safety.

“Around 17 million people in the EU and U.K. 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,” Ann Taylor, the company’s chief medical officer, said in a statement.

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Professor Karina Butler, chair of Ireland’s immunization advisory committee, said the panel made its recommendation while agencies were investigating.

“We will continue to monitor the situation, and if we can be satisfied that these events are coincidental and not caused by this vaccine, we will reassess the situation,” Butler said.

No such cases have been reported to Ireland’s medicine regulators, with more than 117,000 doses of the vaccine administered in the country. Of the newest reports in Norway, one patient died from an unexpected brain hemorrhage, and the three others with severe cases of blood clots or brain hemorrhages were being treated in a hospital, according to the Norwegian Medicines Agency.

That agency issued an advisory for people younger than 50 who had received the AstraZeneca vaccine in the past two weeks, and who feel increasingly unwell with several large blue patches on their skin more than three days after vaccination, to consult doctors or other medical advice as soon as possible.

Ireland joined other European countries in halting the use of the AstraZeneca vaccine in the past week as a precaution because of concerns over the risk of blood clots, although officials there emphasized that there was no evidence yet of a causal link and that the new reports from Norway were being investigated. Thailand delayed its rollout of the vaccine, which was to begin Friday. The Democratic Republic of the Congo has also delayed its rollout, Reuters reported. On Sunday, Italy’s northern region of Piedmont said it would temporarily suspend giving the AstraZeneca vaccine, a day after a teacher there died after receiving the shot.

The European Medicines Agency, which is investigating the relationship, said Wednesday that 30 cases of obstructive blood clots had been reported in the nearly 5 million people who received the shot — a rate no higher than that seen in the general population, and that the vaccine’s benefits outweighed the risks. AstraZeneca has said that its safety data of more than 10 million records does not show evidence of an increased risk of pulmonary embolism or deep vein thrombosis.

In its statement, AstraZeneca also said that as of March 8, the company was aware of 15 reports of deep-vein thrombosis and 22 of pulmonary embolism among those who had received the vaccine across the European Union and Britain. “This is much lower than would be expected to occur naturally in a general population of this size and is similar across other licensed COVID vaccines,” the company said.