Trials resume for AZ/Oxford University COVID-19 vaccine

After a voluntary pause, the MHRA has confirmed that trials can restart


After the Medicines Health Regulatory Authority (MHRA) confirmed that it was safe to do so, clinical trials for the AstraZeneca/Oxford coronavirus vaccine, AZD1222, have resumed in the UK.

A voluntary pause was placed across all global trials on 6 September, triggered by the standard review process. This was to allow a review of the safety data by independent committees and international regulators.

According to a release from AstraZeneca on 12 September: “The UK committee has concluded its investigations and recommended to the MHRA that trials in the UK are safe to resume.”

The release continued: “AstraZeneca is committed to the safety of trial participants and the highest standards of conduct in clinical trials. The Company will continue to work with health authorities across the world and be guided as to when other clinical trials can resume to provide the vaccine broadly, equitably and at no profit during this pandemic.”

The release concluded by stating that “all trial investigators and participants will be updated with the relevant information and this will be disclosed on global clinical registries, according to the clinical trial and regulatory standards”.

The pause was instituted after a patient in the UK suffered a reported side effect. Investigations were conducted to identify if the adverse reaction was linked to the vaccine.

No further medical information was disclosed by AstraZeneca or the University of Oxford, the trial sponsor, for confidentiality reasons.

However, it was reported in the New York Times that the side effect suffered by a participant in the UK trial was transverse myelitis, which can be caused by viral infections and affects the spinal cord.

In a statement, Oxford University said: “In large trials such as this one, it was expected that some participants will become unwell.”

The statement added: “Following the recommendations of both the independent safety review committee and the UK regulator, the MHRA, the trials will recommence in the UK.”

Health Secretary Matt Hancock welcomed the news, saying:"This pause shows we will always put safety first. We will back our scientists to deliver an effective vaccine as soon as safely possible."

The phase 3 trials involve some 30,000 participants in the US, as well as participants in the UK, Brazil and South Africa.

The government's chief scientific adviser, Sir Patrick Vallance, told a Downing Street press conference that what had happened in the Oxford trial was not unusual. He added that similar events should also be expected in some of the other vaccine candidate trials.