The World Health Organization's vaccine safety experts were due to meet Tuesday to discuss the Oxford-AstraZeneca Covid-19 vaccine, as the list of countries temporarily halting its rollout over blood clot concerns continued to grow.

On Tuesday, Cyprus, Luxembourg, Latvia and Sweden became the latest European nations to suspend its use, despite advice from international medical agencies that the benefits of getting shots into arms outweigh any potential risks.

WHO on Monday appealed to countries to keep vaccination campaigns going, saying there was no evidence the vaccine caused clotting issues.

“As of today, there is no evidence that the incidents are caused by the vaccine and it is important that vaccination campaigns continue so that we can save lives and stem severe disease from the virus,” WHO spokesman Christian Lindmeier said.

WHO is assessing the latest reports of thromboembolic events, but said it was “unlikely” to change its recommendations.

Europe's medicines regulator, the European Medical Authority (EMA), which authorized the use of the shot for the 27-nation bloc, is convening a special meeting Thursday to review information gathered into whether the AstraZeneca vaccine influenced clotting in vaccinated people. The EMA has also advised against halting vaccination campaigns while investigations are ongoing.

But much of Europe has gone against that advice in recent days, temporarily halting AstraZeneca shots even as the continent confronts a third wave of the pandemic, spurred by variants of the virus, and faces criticism over sluggish vaccination campaigns.