Denmark, Norway, and Iceland have paused use of AstraZeneca’s COVID-19 vaccine while investigators look into several cases of blood clots among vaccinated people. Denmark has halted its use of the coronavirus vaccine for at least 14 days in response to the cases, the country’s health authority said Thursday. One of these cases was related to a death in Denmark, it said. This follows Austrian authorities saying Sunday that a 49-year-old woman had died as a result of severe coagulation disorders after taking the shot. Magnus Heunicke, the Danish health minister, said it wasn’t clear whether the blood clots were linked to the vaccine. Around three hours after Denmark’s announcement, Norwegian officials said they would also suspend use of the AstraZeneca vaccine. The Financial Times first reported that Iceland had also suspended the use of the vaccine, and Kjartan Njálsson, assistant to the director of health in Iceland, told CNN that officials were awaiting advice from the European Medicines Agency (EMA). Both the Danish and Norwegian health ministries said that there was good evidence the vaccine, developed by AstraZeneca and Oxford University, was safe and effective but that they must react to reports of possible serious side effects. People who received their first dose of AstraZeneca’s vaccine would have to wait for their second dose during the suspension, Denmark’s health authority said. It added that it was waiting for the results of an investigation by the EMA.

The EMA said that in the European Economic Area, 30 cases of blood clots had been reported out of close to 5 million people vaccinated. UK experts said the proportion of vaccinated people with blood clots was not significantly higher than in the general population.

The vaccine has been granted conditional marketing authorization or emergency use in more than 50 countries, including the UK and across the European Union. It has not yet been issued emergency-use authorization in the US.