Europe's drug regulator on Wednesday found a possible link between AstraZeneca's COVID-19 vaccine and rare blood clotting issues in adults who had received the shot and said it had taken into consideration all available evidence.
"One plausible explanation for the combination of blood clots and low blood platelets is an immune response, leading to a condition similar to one seen sometimes in patients treated with heparin," the European Medicines Agency (EMA) said. The findings come as a major hurdle in the global fight against the pandemic and a shift in the stance of the regulator, which had last week backed the vaccine and said there was no increased risk of blood clots in general from the shot.
It is also a blow to AstraZeneca, which was a frontrunner in the race for making an effective vaccine against COVID-19 ever since it began working with the University of Oxford.
The EMA's safety committee, which was assessing the vaccine, has requested for more studies and changes to the current ones to get more information.
The European drug regulator has received reports of 169 cases of a rare brain blood clot in people who received the AstraZeneca COVID-19 vaccine, a senior official said on Wednesday.
The total for cases of cerebral venous sinus thrombosis (CVST) were recorded as of April 4 out of 34 million doses of the shot administered in the European Economic Area, said Sabine Straus, chair of the European Medicines Agency's (EMA) safety committee.
In London, Britain should not give Oxford University/AstraZeneca's vaccine to under 30s where possible, Britain's Joint Committee on Vaccination and Immunisation (JCVI) said on Wednesday, due to a very rare side effect of blood clots in the brain.
"Based on the available data and evidence, JCVI has advised that it is preferable for adults aged under 30 with no underlying conditions to be offered an alternative to the AstraZeneca vaccine where available," said Wei Shen Lim, COVID-19 Chair for JCVI.
"We are not advising a stop to any vaccination for any individual in any age group. We are advising a preference for one vaccine over another vaccine for a particular age group, really out of the utmost caution, rather than because we have any serious safety concerns," he said at a briefing.
He said people should continue to have a second dose of the AstraZeneca shot if they had received a first dose.
Chief executive June Raine said that the benefits of the shot outweighed the risks for the vast majority.
More to follow...