The U.K. reported 25 new cases of rare blood clots possibly linked to AstraZeneca Plc's Covid-19 vaccine, adding to the numbers that have caused some European countries to adopt precautionary measures.

The fresh reports lift the total number of cases to 30 as of March 24, the Medicines and Healthcare Products Regulatory Agency said in a statement Thursday. The benefits of the shot continue to outweigh the risks, the regulator said.

AstraZeneca's vaccine, developed with the University of Oxford, is under mounting scrutiny and has faced dwindling support in Europe. Still, countries are counting on the shot to help them exit the pandemic, and millions of doses have been administered across the region.

The U.K. agency said that the 30 incidents were out of 18.1 million doses of AstraZeneca vaccine given by March 24. Prior to that, the agency disclosed five cases on March 18, out of 11 million shots.

With the new reports, the rate of incidents with the AstraZeneca shot in the U.K. is about 1 in 600,000. There were no reports of the same reactions to the vaccine from Pfizer Inc. and BioNTech SE, which is also being used in Britain.

"On the basis of this ongoing review, the benefits of the vaccines against Covid-19 continue to outweigh any risks and you should continue to get your vaccine when invited to do so," the MHRA said. The AstraZeneca and Pfizer vaccines have shown "very high levels of protection" against Covid-19, the agency said, adding that "all vaccines and medicines have some side effects."

U.K. Program

The U.K. has one of the world's fastest-moving vaccine programs, administering shots to more than half of all adults by late March. New daily Covid cases and deaths have fallen to the lowest levels since September, even as infections surge anew across much of the European Union, where immunizations have lagged.

Earlier this week, the EU drugs regulator said a link between the AstraZeneca vaccine and a rare type of blood clot is possible, identifying at least 62 cases of the condition. The European Medicines Agency said its safety committee will probably issue an updated recommendation next week.

Germany has restricted younger people from taking the AstraZeneca vaccine amid growing concerns about side effects. That followed reports of 31 cases of the rare clots, mostly in women.

Norway and Denmark extended suspensions on the use of the shot, which has also been the subject of a tussle over supplies between the EU, the U.K., and others.

On Friday, Australia reported one case of clotting disorders following inoculation with the AstraZeneca vaccine and is investigating, according to a joint statement by government agencies.