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Wits University pauses Oxford Covid-19 vaccine trial as part of standard regulatory procedure

- Wits University

Wits University will pause the Covid-19 vaccine trial it is running with the University of Oxford following a medical event in a volunteer in the UK.

The Ox1nCov19 trial, led in South Africa by Professor Shabir Madhi, Executive Director of the Vaccines and Infectious Diseases Analytics Research Unit (VIDA), will be paused as part of standard regulatory procedure designed to uphold the safety of participants.

Following a medical event experienced by a participant involved in the study of the ChAdOx1-CoV19 vaccine in the UK, the independent Data and Safety Monitoring Committee (DSMC) has recommended that all studies which they are overseeing pause further vaccination. This will allow the DSMC to undertake a thorough review of the case in the UK.

The details of the medical event that the participant in the UK experienced may not be divulged as this contravenes patient confidentiality.

Because the South African study is overseen by the same safety committee, all sites in the country have paused further vaccination.

“South African trial volunteers who are scheduled to receive either a first or second dose of the vaccine have been notified and we are in regular communication with them as to when vaccination will resume. This decision will be based on the DSMC’s recommendation. Ensuring the safety of all our study participants is our highest priority,” says Madhi.

“Pausing vaccination to review safety is evidence of the application of sound clinical practice and demonstrates the rigour of the independent oversight process under which this trial is being conducted. Assessing the safety of the vaccine is the reason why studies such as these are essential in South Africa, before there is widespread use of the vaccine.”

A spokesperson at the University of Oxford, which leads the trial in the UK and where a participant experienced the medical event, said:

“As part of the ongoing randomised controlled global trials of the coronavirus vaccine, our standard review process triggered a study pause to vaccination to allow review of safety data. 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. In large trials illnesses will happen by chance but must be independently reviewed to check this carefully. We are committed to the safety of our participants and the highest standards of conduct in our studies.”

About the South African Ox1nCov19 vaccine trial

Wits University announced South Africa and Africa’s first Covid-19 vaccine trial, the so-called ‘Oxford trial’, on 23 June 2020.

In South Africa, the study aims to enroll up to 2020 participants at up to seven sites in Gauteng and the Western Cape provinces.

In Gauteng, the sites are in Hillbrow, Soweto, and Tshwane.

In the Western Cape, the sites are in Cape Town and Stellenbosch.

The trial tests if the vaccine known as ChAdOx1 nCoV-19 is safe and able to protect people from developing Covid-19 illness.

The trial will also provide valuable information on whether the body generates good immune responses against the virus.

All South African trial volunteers have provided written informed consent to participate in the trial.

Participant safety a priority

Although the development of this vaccine is on accelerated timeline to address an unprecedented pandemic, the clinical development of the vaccine has built-in reviews processed by the independent international DSMC, as well as regulatory oversight locally by the South African Health Products Regulatory Authority (SAPHRA) and the University of the Witwatersrand Human Research Ethics Committee. The vaccine will only be licensed for use after adequate studies have been undertaken to confirm its safety and effectiveness. 

Status of the South African Ox1nCov19 vaccine trial

The enrolment statistics of this trial as at 9 September 2020 are as follows:

  • 2 886 volunteers screened
  • 1 814 of required 2020 enrolled
  • 1800 out of 1970 (91%) enrolled are HIV negative
  • 14 out of 50 (28%) enrolled are HIV positive

About the ChAdOx1 nCoV-19 vaccine

The technical name of the vaccine is ChAdOx1 nCoV-19 because it made from a virus called ChAdOx1, which is a weakened and non-replicating version of a common cold virus (adenovirus).

The vaccine has been engineered to express the SARS-CoV-2 spike protein.

The vaccine was made by adding genetic material – called spike glycoprotein – that is expressed on the surface of SARS-CoV-2 to the ChAdOx1 virus.

This spike glycoprotein is usually found on the surface of the novel coronavirus and is what gives the coronavirus its distinct spiky appearance.

These spikes play an essential role in laying a path for infection by the coronavirus. The virus that causes Covid-19 uses this spike protein to bind to ACE2 receptors on human cells.

ACE2 is a protein on the surface of many cell types. It is an enzyme that generates small proteins that then go on to regulate functions in the cell. In this way, the virus gains entry to the cells in the human body and causes Covid-19 infection. 

Researchers have shown that antibodies produced against sections of the spike protein after natural infection are able to neutralize (kill) the virus when tested in the laboratory.

By vaccinating volunteers with ChAdOx1 nCoV-19, scientists hope to make the human body recognise and develop an immune response (i.e., develop antibodies) to the spike glycoprotein that will help stop the SARS-CoV-2 virus from entering human cells and causing Covid-19.