Oxford team to inject virus into healthy volunteers in last trial for Covid-19 vaccine
London, July 17, 2020 (AltAfrica)-Hopes for a successful covid-19 vaccine have been raised after University of Oxford researches signalled a potential breakthrough while testing their prototype. The news comes on the heels of similarly strong results from a study in the United States.
Human trials carried out by Oxford researchers reportedly showed their vaccine prototype had successfully generated an immune response against the virus.
But in a last push for breakthrough, the team hope to begin tests on volunteers who will be intentionally exposed (injected) to the virus in a “challenge trial”, a move seen as controversialsince there is no proven cure for the illness.
Although challenge trials, in which healthy volunteers are given a pathogen, are routine in vaccine development, taking the approach for Covid-19, where there is no failsafe treatment if a volunteer becomes severely ill, has been questioned.
In human challenge trials volunteers are intentionally exposed in a controlled laboratory setting, meaning the trial can be completed in weeks and requires far fewer people.
The Oxford vaccine has already been tested in a phase-one trial involving about 1,000 British volunteers, with full details due 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 US for a further stage of testing, known as phase three.
Britain’s Daily Telegraph newspaper said blood samples taken from some 1,000 volunteers in phase 1 trials showed the vaccine had stimulated encouraging levels of antibodies and T-cells. No serious side effects were reported.
Oxford’s Covid-19 vaccine, devised by Sarah Gilbert, is months ahead of the competition https://t.co/ZK9xGJvMnj— Businessweek (@BW) July 15, 2020
A senior team member has said that preparations have begun for the human challenge trial to run in parallel with phase three, which would require only tens of volunteers to test the efficacy of the vaccine.
Prof Adrian Hill, director of Oxford University’s Jenner Institute, said that Oxford scientists were working in the laboratory on the technical side of preparation for such a trial and that the team 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.”
Prof Adrian Hill says the challenge trial will be complementary with a coronavirus trial which has recruited participants in Brazil and South Africa. Photograph: Eddie Keogh/Reuters
A growing number of scientists, including members of the Oxford team, argue that the human challenge trial approach is justified given that the risk would be very low for healthy people in their 20s, and since it would be set against the global impact of the pandemic and emergence of treatments such as Remdesivir.
One recent analysis put the risk of death from Covid-19 for someone in their 20s at around one in 3,000, similar to the risk for live kidney donation.
“Everybody would agree that the risk is extremely low in young people,” said Hill. “It’s so low that it’s very difficult to measure.”
The development comes amid speculation that the publication of the Oxford team’s phase one trial results on Monday will reveal “positive news”. The results are expected to show that there are no serious side-effects from this vaccine and that subjects show a response in each aspect of the immune system, the antibodies and T-cells.
This conclusion would be in line with the results of animal studies released so far, but even if a robust immune response were confirmed, it would not be a guarantee that the vaccine protected against infection. Instead such protection could be established in the phase three trial. This phase has recruited 10,000 trial participants in the UK, about 5,000 in Brazil and 2,000 in South Africa, with a second trial in the US aiming to recruit as many as 30,000 participants.
“We now know the Oxford vaccine covers both bases – it produces both a T-cell and an antibody response,” an unnamed source told the Telegraph. A separate source said this meant the vaccine could offer “double protection” against the virus.
While the researchers have yet to prove the immune response is enough to offer long-lasting protection against infection, the results are much more encouraging than dozens of similar Covid-19 trials.
In a public statement, the Oxford team said the results of the trial were expected to be published next week in The Lancet medical journal.
A leader contender among almost 100 prototypes currently in development, the vaccine is being supported by the British government and pharmaceutical giant AstraZeneca.
US trial enters ‘final stages’
News of the Oxford trial results come after US biotech company Moderna said its Covid-19 vaccine was ready to enter the final stage of human trials.
Strong early results published in the New England Journal of Medicine showed the vaccine induced an immune responses in all of the volunteers who received it in a phase 1 study.
The company said it would enter final human trials on 27 July, to test how well the vaccine protects people in the real world.
Some 30,000 participants are to be recruited in the US, half of whom will receive a placebo, and the other half of whom will receive a 100 microgram dose of the vaccine.
So far, the coronavirus has infected more than 13.5 million people and killed 580,000 people worldwide