AstraZeneca halts vaccine testing due to adverse reaction in a participant

(Patria) – Pharmaceutical company AstraZeneca has halted global clinical trials of its experimental vaccine against the Covid-19 virus due to a severe adverse reaction in one of the trial participants.

The vaccine, developed by the British company AstraZeneca in collaboration with the University of Oxford, has been described by the World Health Organization as a leading candidate among the vaccines currently being developed against the coronavirus.

Details of the reaction to the vaccine in the trial participant are not known to the wider public, but it is expected that they will fully recover.

According to the New York Times, which quotes a person familiar with the circumstances, the trial participant from Great Britain was diagnosed with transverse myelitis, an inflammatory syndrome that attacks the spinal cord.   

However, it is still unclear whether the illness is directly related to the AstraZeneca vaccine. The company declined to comment.

AstraZeneca shares fell by 8% in the US in just a few hours after the event, while shares of the pharmaceutical company Moderna, which is also developing a vaccine, rose by 4% almost simultaneously.

The development of the AZD1222 vaccine had already entered the final phase of clinical trials in the US, Great Britain, Brazil, and South Africa, with additional trials planned in Japan and Russia.

Around 50,000 volunteers worldwide will participate in further trials.