AstraZeneca's vaccine is safe, Europe's regulator said following an investigation into potential side effects. 18 countries could now lift their suspensions of the shot.

• AstraZeneca's COVID-19 vaccine is safe, the European medicines regulator said Thursday.
• The European Medicines Agency's statement followed an investigation of blood clots in vaccinated people.
• Eighteen countries that had paused use of the shot could now lift their suspensions.

AstraZeneca and Oxford University's COVID-19 vaccine is safe and its benefits clearly outweigh its risks, the European regulator said Thursday.

The European Medicines Agency (EMA) said in a press briefing that AstraZeneca's vaccine was not associated with a higher risk of blood clots, following an investigation into reports that people who had received the vaccine developed clots.

The number of clots reported after vaccination, both in trial studies and during the roll out of the shot, was lower than that expected in the general population, the EMA said.

However, the EMA said it still could not definitively rule out a link between the vaccine and reported rare cases of very serious clotting, specifically blood clots associated with low levels of blood platelets. This was especially a concern in younger people, it said.

It had launched additional reviews and lab tests, it said. It would also add a warning to patient leaflets and the information distributed to health professionals so that people could spot possible signs and symptoms associated with a blood clot, it said.

At least 18 countries worldwide - including Sweden, Germany and France - had suspended the vaccine as a precaution, pending the EMA's investigation. Many of those countries said that suspensions would be lifted if the EMA concluded the vaccine was safe.

"The benefits of the AstraZeneca vaccine in preventing COVID-19, with its associated risk of hospitalization and death, outweigh the risks of side effects," the EMA said - a view that the regulator has maintained throughout.

EMA Executive Director Emer Cooke said that she would be "vaccinated tomorrow."