On September 6, the standard review process triggered a voluntary pause to vaccination across all global trials to allow review of safety data by independent committees, and worldwide regulators, a statement by AstraZeneca says.
Last week, Oxford temporarily paused its large-scale vaccination tests after one participant in the United Kingdom reported severe neurological symptoms; it was restarted on Sunday.
Similar vaccines made by Moderna and Pfizer/BioNTech are at a similar stage of testing.
The Briton who suffered the potentially risky side effects is expected to recover, but Oxford University says it "cannot disclose medical information about the illness for reasons of participant confidentiality".
The biggest drugmakers in the hunt for a COVID-19 vaccine have been racing to lock up national supply deals for months in anticipation of global demand for a victor. The messenger RNA or mRNA-based vaccine entered phase-3 trial on July 27 with active help from the USA government. The vaccine, co-developed with National Institute of Allergy and Infectious Diseases, underwent trials at 89 sites across the US. Later in August, the Donald Trump administration struck a $1.525 billion deal with the Massachusetts-based company for 100 million doses of its Covid-19 vaccine. The company is also in talks with Japan and European Commission to supply 120 million doses of the vaccines post approval.
The World Health Organization has named the vaccine being developed by AstraZeneca in partnership with the University of Oxford as probably the most promising in the world and the most advanced in terms of development.
"This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the studies, while it is investigated, ensuring we maintain the integrity of the trials". Their mRNA-based vaccine candidate "BNT162" is in late-stage trials in US, Brazil, Argentina and Germany.
Serum Institute has a production and distribution alliance on this vaccine candidate in low- and middle-income countries. He tweeted: "Good news for everyone, the Oxford vaccine trials are back up and running". The suspension of trials is impairing the prospects for early market launch of this vaccine.
Dr. Charlotte Summers, a lecturer in intensive care medicine at the University of Cambridge, said the pause was a sign that the Oxford team was putting safety issues first, but that it led to "much unhelpful speculation".
Calling it a "wake-up call" of sorts, Dr Soumya Swaminathan, Chief Scientist with the World Health Organisation, said the development was "perhaps a lesson for everyone to recognise the fact that there are ups and downs in research, ups and downs in clinical development and we have to be prepared for those".