Oxford University Covid-19 vaccine trial put on hold after participant falls ill

Wednesday September 09 2020

This picture taken on May 23, 2020 shows a laboratory technician filling a syringe with a Covid-19 vaccine candidate ready for trial on monkeys at the National Primate Research Center of Thailand at Chulalongkorn University in Saraburi. PHOTO | MLADEN ANTONOV | AFP


A large study testing a coronavirus vaccine developed by Oxford University and AstraZeneca has been paused after a participant had a suspected adverse reaction in the United Kingdom.

Although AstraZeneca described it as a “routine” pause in the case of “an unexplained illness”, the halt has triggered fears of delays in finding a solution to the Covid-19 pandemic.

A spokesperson for the British-Swedish multinational pharmaceutical said in a statement that the company’s “standard review process triggered a pause to vaccination to allow the review of safety data.”

Hopes have been high that the AstraZeneca-Oxford University vaccine might be one of the first, among dozens being developed globally, to hit the market, following successful phase one and two testings. 

Last month, AstraZeneca began recruiting 30,000 people in the United States for its largest study as it moved to phase three. It also started testing the vaccine in Britain, Brazil, and South Africa. Kenya also announced it has applied to participate in the Oxford study.

“As part of the ongoing randomised, controlled global trials of the Oxford coronavirus vaccine, our standard review process was triggered and we voluntarily paused vaccination to allow a review of safety data by an independent committee,” said AstraZeneca.


“This is a routine action which has to happen whenever there is a potentially unexplained illness in one of the trials, while it is investigated, ensuring we maintain the integrity of the trials,” the pharmaceutical added.


According to a BBC report, this is the second time such a pause has happened with the Oxford University-AstraZeneca coronavirus vaccine trial since the first volunteers were immunised in April.

“In large trials, illnesses will happen by chance but must be independently reviewed to check this carefully,” said an Oxford University spokesperson.

For now, all international vaccination sites, in the UK, Brazil, South Africa, and the US are on hold until a final decision on restarting the trial is taken by the UK’s medical regulator the Medicines and Healthcare products Regulatory Agency (MHRA).

Two other vaccines which are currently undergoing large testings in the US include one by Moderna Inc, and the other by Pfizer and Germany’s BioNTech. About two-thirds of the needed participants have already been recruited for the studies.

Temporary holds of large medical studies are not unusual as investigations of unexpected reactions among participants are a mandatory safety step. In a follow-up statement, first reported by Stat News, AstraZeneca said it initiated the study hold. Details of the unexplained illness have not been released, and the nature of the adverse reaction and when it happened was not immediately known.

The World Health Organisation (WHO) has reiterated that the safety of a prospective vaccine for Covid-19 comes "first and foremost".

“Just because we talk about speed ... it doesn't mean we start compromising or cutting corners on what would normally be assessed,” Soumya Swaminathan,  the WHO’s chief scientist said during a social media event.