The Oxford AstraZeneca vaccine trial on children has been paused while the UK regulator investigates possible links to rare blood clots in adults.

Around 300 volunteers had signed up for the trials which started in February with the purpose of assessing whether the jab produces a strong immune response in children aged between six and 17.

Professor Andrew Pollard from the University of Oxford told the BBC that there were no safety concerns with the trial itself, but its scientists were waiting for further information.

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Participants have been advised to continue to attend all scheduled visits and can contact the trial sites if they have any questions.

The University of Oxford said that no safety concerns have arisen from the trial itself.

But it is waiting for more information from the Medicines and Healthcare products Regulatory Agency (MHRA) before giving any more vaccinations.

Regulatory bodies from the UK, Europe and the World Health Organisation (WHO) are assessing data on the jab and a potential association with a rare form of blood clot.

The WHO and the European Medicines Agency (EMA) have confirmed they will publish findings later this week.

The University of Oxford said in a statement: “Whilst there are no safety concerns in the paediatric clinical trial, we await additional information from the MHRA on its review of rare cases of thrombosis/thrombocytopaenia that have been reported in adults, before giving any further vaccinations in the trial.

“Parents and children should continue to attend all scheduled visits and can contact the trial sites if they have any questions.”

The Herald previously reported that more people have experienced side-effects from the Oxford AstraZeneca vaccine than the Pfizer drug.


According to data from the King's College London's Zoe tracking app and involving 700,000 UK participants, found that women, younger people and those who have already had Covid-19 were more likely to experience side-effects from both vaccines.

The data showed that around three in ten people who received the Oxford vaccine reported negative side-effects such as headaches, chills and tiredness compared to one in ten who received the Pfizer vaccine.