The World Health Organization on Friday said that there was no reason to stop using the AstraZeneca coronavirus vaccine after several European countries temporarily suspended its use amid concerns of patients developing blood clots after inoculation.

The WHO said its vaccines advisory committee was looking at the safety data. It said that no causal link has yet been established between the clotting and the vaccine.

“AstraZeneca is an excellent vaccine, as are the other vaccines that are being used,” WHO spokesperson Margaret Harris said. “We’ve reviewed the data on deaths. There has been no death, to date, proven to have been caused by vaccination.”

Harris, however, said that any safety concerns about the vaccines should be investigated. “We must always ensure that we look for any safety signals when we roll out vaccines, and we must review them,” she added.

On Thursday, countries such as Denmark, Norway and Iceland had temporarily suspended the use of AstraZeneca’s coronavirus vaccine. Other countries such as Austria, Estonia, Latvia, Lithuania and Luxemburg, however, had not completely suspended the use of the vaccine but stopped using just one batch sent to 17 European countries, containing one million, or 10 lakh, shots.

Austria took the decision on Monday after a 49-year-old nurse, who had received the jab from the batch concerned, died of “severe blood coagulation problems”. Another person who received a shot from the same vaccine batch was also hospitalised because of a blood clot.

The European Medicines Agency, or EMA, said that as of March 9, 22 cases of blood clots have been reported from among the 3 million, or 30 lakh, vaccinated in the European Economic Area, comprising the European Union and three countries of the European Free Trade Association excluding Switzerland.

AstraZeneca, which developed the vaccine with Oxford University, had defended the product. “The safety of the vaccine has been extensively studied in phase III clinical trials and peer-reviewed data confirms the vaccine has been generally well-tolerated,” a spokesperson for the company told AFP.

Britain also defended the vaccine, calling it “both safe and effective”. Professor Anthony Harnden, a member of the UK-based Joint Committee on Vaccinations and Immunisations, said that there was no reason to worry about the safety of the vaccine.

In India, the AstraZeneca-Oxford vaccine is one of the two vaccines approved for emergency use. Covaxin, developed by Bharat Biotech in collaboration with the Indian Council of Medical Research and the National Institute of Virology, is the other vaccine.