Call for COVID-19 'challenge trial' ahead of AstraZeneca vaccine readout

SARS-CoV-2 coronavirus

Press reports suggest that there is good news about AstraZeneca and Oxford University’s COVID-19 vaccine due from an early stage trial in the coming days – but the focus is moving on how to get the in-depth safety and efficacy results needed to get the jab formally approved. 

According to the press reports, the phase 1 trial results suggest the vaccine produces an immune response including both antibodies and T-cells with few side-effects.

Further details are due to be published in The Lancet, according to the journalist Robert Peston, who broke the story. 

This twin effect could be the key to lasting immunity against the virus, with the T-cells able to attack the virus even if the body has stopped producing antibodies that neutralise it. 

AZ’s vaccine is one of the front-runners in a growing list of vaccines that have been rushed into clinical trials, when development began almost immediately after Chinese scientists published the virus’s genetic details in January. 

The vaccine is already in phase 3 development and the company is busy recruiting tens of thousands of people in the UK, Brazil, South Africa, and the US. 

According to The Guardian, the next step is to begin a controversial “challenge trial” where healthy subjects are given the vaccine and then exposed to the virus to test to test the levels of protection it confers. 

These trials are conducted in a lab and can be completed in a few weeks, requiring far fewer people. 

This is important because in countries where lockdown measures have been successful in controlling the spread of the SARS-CoV-2 virusit is becoming difficult to gather the data showing whether the vaccine is effective or not. 

Professor Adrian Hill, director of Oxford University’s Jenner Institute, told The Guardian that scientists are already preparing the trial and aim to get it up and running by the end of the year. 

He said: “This might be in parallel or might be after the phase three trial is completed. They’re not competing options, they’re complementary.” 

The Oxford team is among a growing group of scientists who argue that human challenge is justified given the low risk of serious complications or death for healthy people in their twenties. 

The World Health Organization has already produced guidance on challenge trials that suggests that risk of death from COVID-19 is approximately one in 3,000, around the same for live kidney donation. 

Hill said the risk is “so low that it’s very difficult to measure” and is among the signatories of an open letter from US-based campaign group 1Day Sooner, which is promoting challenge trials to accelerate development of a COVID-19 vaccine. 

Other signatories include the Nobel laureate and biologist Sir Richard Roberts, the renowned surgeon and former health minister Lord Darzi. 

Feature image courtesy of Rocky Mountain Laboratories/NIH