A World Health Organization (WHO) advisory group statement on the AstraZeneca COVID-19 shot is expected very soon, a WHO spokesman said on Wednesday.

Global health experts have come under increasing pressure to clear up questions over the safety of AstraZeneca's vaccine, as the number of countries suspending its use grows in a blow to Europe's vaccination rollout.

The European Medicines Agency has said it is investigating reports of 30 cases of unusual blood disorders out of 5 million recipients of the AstraZeneca vaccine. In total, 45 million COVID shots have been delivered across the region.

Kate O'Brien, director of WHO's Department of Immunization, Vaccines and Biologicals, said that a WHO vaccine safety panel that met on Tuesday was assessing whether medical events such as blood clots were actually related to vaccination.

"We should not over-interpret these specific numbers that come out of trials. They are highly effective vaccines, they are life-saving vaccines, they are safe vaccines and we should get on with deploying them," she told a news conference.

"So, anybody who is offered vaccine should take whatever is being offered by the program and ensure that the vaccines that are being produced, are used to their maximum benefit," she said.

WHO said on Wednesday that it still recommends using the AstraZeneca vaccine against COVID-19 as the benefits outweigh its risks.