European and British medicine regulators said on Wednesday they found possible links between AstraZeneca's coronavirus vaccine and reports of very rare cases of brain blood clots, in a setback for inoculation campaigns.

A British government advisory group said the vaccine should not be given to those under 30 where possible, though an official said this was "really out of the utmost caution, rather than because we have any serious safety concerns".

More than a dozen countries have suspended the use of the vaccine...