Dhaka, March 22 -- The polling firm YouGov said it had already found in late February that Europeans were more hesitant about the AstraZeneca vaccine than about those from Pfizer Inc /BioNTech and Moderna Inc, and that the clot concerns had further damaged public perceptions of the AstraZeneca shot's safety.

At least 13 European countries in the past two weeks stopped administering the AstraZeneca shot, co-developed with scientists at Oxford University, after reports of a small number of blood disorders.

Many resumed its use on Friday after the European Medicines Agency regulator said in a preliminary safety review on Thursday that the vaccine was safe and effective and not linked with a rise in the overall risk of blood clots.

EMA did...