LONDON (VINnews) —The Oxford University team which published positive results from its Phase I human trials this week hopes to begin tests later this year on volunteers who will be intentionally exposed to the virus in a controversial process known as a “human challenge trial” by which healthy volunteers are placed under extremely precautious laboratory conditions, with measured viral loads and a whole host of other restrictions. The virus is exposed to these volunteers who don’t have pre-existing conditions and have developed antibodies since vaccination.
Although challenge trials are a routine aspect of vaccine development, in the case of Covid-19, where there is as yet no foolproof treatment if a volunteer becomes severely ill, the move has been questioned. However the risk of complications is low, with one recent analysis putting the risk of death from Covid-19 for someone in their 20s at around one in 3,000, similar to the risk for a live kidney donation.
The advantage of such trials is that they speed up the process of measuring the effects of the vaccine, meaning that the trial can be completed within a few weeks and require less people that regular trials.
Adrian Hill, director of Oxford Jenner Institute which is developing the vaccine,told the Guardian that his team were working on the technical side of the preparation for a human challenge trial, and it hoped to recruit volunteers within months.
“We’re hoping to be doing challenge trials 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.”
An open letter written by 125 academics, doctors, epidemiologists, scientists, and professors, including 15 Nobel laureates, was recently addressed to the US’s National Institute of Health (NIH) asking for human challenge trials to take place in order to expedite the vaccine required to curb the pandemic.
“If challenge trials can safely and effectively speed the vaccine development process, there is a formidable presumption in favour of their use, which would require a very compelling ethical justification to overcome,” they wrote.