AstraZeneca has resumed all clinical trials of its coronavirus vaccine candidate after the Food and Drug Administration (FDA) authorised the restart in the US.

The FDA authorisation follows the resumption of trials in other countries over the last few weeks. After reviewing all safety data from the global trials, the FDA concluded that it was safe to resume the large-scale trial.

On 6 September, a voluntary pause to vaccination occurred across all global trials after a participant in the UK arm of AZ’s programme experienced a serious adverse event.

This pause allowed independent monitoring committees to examine all safety data, with the recommendations from these reviews having been supported by international regulators, who confirmed that the trials were safe to resume.

The vaccine candidate, AZD1222, was co-invented by the University of Oxford and its spin-out company Vaccitech.

It uses a replication-deficient chimpanzee viral vector based on a weakened version of an adenovirus (the common cold virus) that contains the genetic material of SARS-CoV-2 virus spike protein, which causes COVID-19.

AZ said in a statement that results from the phase III trials are expected later this year, depending on the COVID-19 infection rate in the communities where the studies are being conducted.

Currently, rolling reviews of AZ’s vaccine programme have already started in countries where this regulatory pathway has been established, with the company providing regulators access to data as soon as they become available.