The team behind the Oxford Covid-19 vaccine hopes to start tests on volunteers who will be intentionally exposed to the virus during a challenge challenge, a process considered controversial. because there is no proven cure for the disease.
Although provocation trials, in which healthy volunteers receive a pathogen, are common in vaccine development, adopting the approach for Covid-19, where there is no foolproof treatment if a volunteer fell seriously ill, was questioned.
In human provocation trials, volunteers are intentionally exposed in a controlled laboratory, which means that the trial can be completed in a few weeks and requires far fewer people.
The Oxford vaccine has already been tested in a phase 1 trial involving around 1,000 British volunteers, and full details are expected to be published in The Lancet on Monday. Tens of thousands of people are also being recruited in the UK, Brazil, South Africa and the United States for a new test step, called phase three.
A senior team member said preparations have started for the human challenge trial to run in parallel with phase three, which would only require dozens of volunteers to test the vaccine’s effectiveness.
Professor Adrian Hill, director of the Jenner Institute at the University of Oxford, said that the Oxford scientists were working in the laboratory on the technical side of the preparation of such a trial and that the team hoped to recruit volunteers in the coming months.
“We hope to have provocation tests by the end of the year,” he said. “It could be in parallel or after the end of the phase three trial. These are not competing options, they are complementary. “
A growing number of scientists, including members of the Oxford team, argue that the approach to human provocation testing is warranted as the risk would be very low for healthy people in their twenties and that he would oppose the global impact of the pandemic. and the emergence of treatments such as Remdesivir.
A recent analysis estimated the risk of death from Covid-19 for a person in their twenties at approximately one in 3000, similar to the risk of living kidney donation.
“Everyone would agree that the risk is extremely low among young people,” said Hill. “It is so low that it is very difficult to measure.”
The move comes amid speculation that the Oxford team’s phase 1 trial results will be released on Monday “positive news”. The results should show that there are no serious side effects from this vaccine and that subjects have a response in every aspect of the immune system, antibodies and T cells.
This conclusion would be consistent with the results of animal studies published to date, but even if a robust immune response was confirmed, it would not guarantee that the vaccine protects against infection. Instead, such protection could be established in phase three of the trial. This phase recruited 10,000 trial participants in the United Kingdom, approximately 5,000 in Brazil and 2,000 in South Africa, a second trial in the United States aimed at recruiting up to 30,000 participants.
The timing of the phase three trial depends on waiting for a sufficient number of participants exposed to the coronavirus in daily life, which should reveal whether those who received the vaccine (rather than a placebo) are protected. It can take months depending on the levels of infection in the community.
Hill said the challenge trial, starting either after or in parallel with the phase three trial, could provide additional information on the optimal dosage and administration of the vaccine, as well as being a means of testing the duration immunity to the virus after exposure or vaccination.
AstraZeneca has agreed to supply 100 million doses of the Oxford vaccine to Britain, with manufacturing plans already underway and delivery scheduled for September or October. The AstraZeneca agreement will supply the United States with doses of 300 million.
Hill is among the signatories to an open letter published today by Nobel laureates and veteran scientists, coordinated by the American campaign group 1Day Sooner, which promotes human provocation trials to accelerate vaccine development Covid-19.
The letter states, “If challenge trials can speed up the process of developing vaccines safely and effectively, then there is a formidable presumption in favor of their use, which would require very convincing ethical justification to be overcome.”
Other signatories include several prominent British scientists, including Nobel laureate and biologist Sir Richard Roberts, Lord Darzi, director of the Institute of Global Health Innovation at Imperial College London, Professor Peter Openshaw of the ‘Imperial College and Oxford ethicist Julian Savulescu.