Mohamed Ibrahim Bassyouni
2020 / 7 / 21
In conjunction with the very good results from the Oxford vaccine developers, they also announced their willingness to enter the Human Challenge trial phase.
Volunteers deliberately infected with the virus to see the effectiveness of the vaccine.
To understand why such an action was taken, review with you the steps to adopt the vaccine in a brief, simplified manner.
After the completion of laboratory experiments on animals, the transition to the first stage of testing in humans will take place on a-limit-ed number of volunteers, which is to ensure the safety and effectiveness of the vaccine and also side effects.
The second stage: It is based on a larger number of volunteers up to 700 people, which is essential to understand whether the doses need to be modified to provide the required protection, also how many doses are required and the time between each dose.
The third stage: before accreditation, usually on a larger segment of society, including children, adults, and the elderly, who may number 30,000 volunteers.
These volunteers are constantly monitored to see if they are sick´-or-not. This stage needs a very long time.
Most of the countries that develop the vaccine need time during this phase, and at the same time the number of active cases decreases, which leads to delaying the development of vaccine production to more than six months, and this is what happened with China, which agreed with the UAE and Britain, which agreed with Brazil, here the problem was And the emergence of a difficult solution. The proposed solution was the Human Challenge experiment, a solution that had previously been used in ancient diseases such as malaria, cholera and typhoid. The difference here. These diseases have a cure if the symptoms of the disease appear on the volunteers, but the problem in Covid 19 is that it has no cure at the moment. That is, if serious symptoms appeared on a volunteer that might cost him his life, this point was the subject of disagreement among scientists, so it is important to choose patients from the young age group between 18 and 30 years without any chronic diseases, the percentage of serious symptoms appearing between this group is small, but it is not zero.
Human challenge method: A small group of volunteers will be divided into two groups.
1- A group vaccinated
2- A group without vaccine
After the formation of the immune reaction after a period, they will be injected with the virus and observed to see who will develop the symptoms of the disease from both groups. You will be in a specialized facility and fully equipped to avoid any damage. This method will accelerate the process of adopting the vaccine approximately six months from the usual method, also one of its advantages is that it needs a small number of volunteers.
The Oxford vaccine has already been tested in a first-stage trial that involved around 1,000 British volunteers, and full details are to be published in the Lancet magazine soon. Tens of thousands of people are also being recruited in the United Kingdom, Brazil, South Africa and the United States for another stage of the test, known as the third stage.
A senior team member said that preparations had begun to conduct the human challenge trial in parallel with the third stage, which would require only dozens of volunteers to test the effectiveness of the vaccine.
Professor Adrian Hill, -dir-ector of the Jenner Institute at Oxford University, said that Oxford scientists are working in the laboratory on the technical side of preparing for such an experiment, and that the team hopes to recruit volunteers within months.
He said: "We hope to conduct challenging tests by the end of the year." "This may be parallel´-or-it may be after the completion of the third stage of the experiment. They are not competitive options, they are complementary."
Professor Adrian Hill says the challenge trial will complement the experience of the Coronavirus, which has recruited participants in Brazil and South Africa.
An increasing number of scientists, including Oxford team members, argue that the human challenge test approach is justified given that the risk will be very low for healthy people in their twenties, and that it will be against the global impact of the epidemic and the emergence of treatments such as Remdesivir.
A recent analysis put the risk of death from Covid-19 to a person in their twenties at one in every 3,000, similar to the risk of a live kidney donation.
"Everyone will agree that the risk is very low for young people," Hill said. "It is too low to be measured."
This development comes amid speculation that publishing the results of the first phase of the Oxford team soon this week will reveal "positive news." The results are expected to show that there are no serious side effects to this vaccine and that people show a response in every aspect of the immune system, antibodies, and T cells.
This finding is consistent with the results of animal studies so far, but even if a strong immune response is confirmed, this will not be a guarantee of vaccine protection against infection. Alternatively, this protection can be demonstrated in the third stage of the experiment. This stage has recruited 10,000 participants in the experiment in the UK, about 5,000 in Brazil and 2000 in South Africa, with a second experiment in the United States aimed at recruiting up to 30,000 participants.
The phase III trial schedule is based on waiting for a sufficient number of participants to be exposed to coronavirus in daily life, which should reveal whether those who received the vaccine (instead of placebo) are protected. This may take months, depending on infection levels in the community.
Hill said that the challenge trial, which begins either after´-or-in parallel with the third stage of the experiment, can provide supplementary information about optimal doses and vaccine administration, as well as a way to test how long the immunity against the virus continues after exposure´-or-vaccination.
AstraZeneca has agreed to supply 100 million doses of Oxford vaccine to Britain, with manufacturing plans already starting and delivery is scheduled for September´-or-October. The AstraZeneca deal will provide the United States 300 million doses.
Hill is among the signatories to an open letter published by Nobel Prize Laureates and leading scientists, coordinated by the US-based Campaign Group, which promotes human-trial trials to accelerate the development of the Covid-19 vaccine.
The letter states: "If challenge trials can accelerate the safety and efficacy of the vaccine development process, there is an enormous assumption in favor of its use, which requires a very convincing moral justification to overcome it."
Among the other signatories are several prominent British scholars, including Nobel Prize winner and biologist Sir Richard Roberts, Lord Darzi, -dir-ector of the World Health Innovation Institute at Imperial College London, Professor Peter Oppenshaw, of Imperial College, and Ethics of Biology at Oxford Julian Savulescu.