Trials worldwide were paused on September 6, after a standard review process triggered a voluntary pause to vaccination to allow a review of safety data following a ‘potentially unexplained illness’ in a participant.
On Saturday (September 12), AstraZeneca announced clinical trials for AZD1222 had resumed in the UK following approval from the Medicines Health Regulatory Authority (MHRA). As of this morning, however, it had not received the green light from regulators in the US, South Africa or Brazil to restart late-stage trials in these countries; and was not able to comment on when this was likely to be.
"The Company will continue to work with health authorities across the world and be guided as to when other clinical trials can resume," said the British-Swedish company in a statement.
AstraZeneca and the University of Oxford have not disclosed any medical information on the nature of the illness. Last week AstraZeneca highlighted that the pause was a 'routine action' following an unexplained event.
US trial remains on hold
AstraZeneca’s 30,000 people Phase 3 trial in the US – which had only been running a week before the safety pause – remains on hold.
A total of 50,000 people are due to participate globally in the trials.
AstraZeneca’s COVID-19 vaccine candidate AZD1222 is one of the most advanced projects in the race to develop a vaccine. AZD1222 uses a replication-deficient chimpanzee viral vector based on a weakened version of an adenovirus. It contains the genetic material of the SARS-CoV-2 virus spike protein. After vaccination, the surface spike protein is produced, priming the immune system to attack the SARS-CoV-2 virus if it later infects the body.
Published before last week's clinical trial pause, AstraZeneca's timeline had anticipated delivery of the vaccine could start by the end of the year. Its global supply capacity is to exceed 2 billion doses. The vaccine is already lined up to supply a number of markets, subject to approval. This includes an agreement to supply 400 million doses to the US and UK, while an agreement with the European Commission last month also pledged the supply of up to 400 million doses. Other recent deals include 33.8 million doses for Australia.