“Infectious challenge”: why the Scientific Council is opposed to this controversial technique in the fight against Covid-19
We know that finding a vaccine takes time. And if the international scientific community is mobilized to achieve this as quickly as possible, a period of at least one to two years remains necessary. In question ? Clinical trials, which are divided into three phases and which make it possible to verify the effectiveness of the said vaccine, are a must.
To speed up this compulsory process, some pharmaceutical companies are proposing to set up an “infectious challenge”. This technique consists of deliberately inoculating the virus into healthy volunteers and evaluating their immune response, in order to test the effectiveness of the vaccine. This process, neglected since the 1970s, is debated.
Accelerate clinical trials thanks to the “infectious challenge”?
The “infectious challenge” takes place in several stages. The first is to separate the volunteers into two groups: one receives the vaccine to be tested, while the other receives a placebo. The virus is then inoculated to all participants. By observing their immune response, scientists can then assess the effectiveness of the vaccine.
While around a hundred Covid-19 vaccines are currently under study, some pharmaceutical companies have suggested using this technique to speed up clinical trials. But the idea is far from appealing to the entire scientific community. In its last opinion issued on July 9, the Scientific Council spoke on the issue and said it was unfavorable to the infectious challenge, for scientific and ethical reasons.
“Infectious challenge”: an “ethical” and “scientific” problem
To explain its positioning, the Scientific Council mentions scientific and ethical reasons. “The existence of animal models of SARS-CoV2 infection, even imperfect, does not require the evaluation of protection in young healthy volunteers, the results of which would not be more transposable than those animal models, to vulnerable people, main targets of protection “, can we read in this document.
The Scientific Council also adds that “even if the level of risk is low, we cannot rule out the possibility of an accident occurring in these volunteers, in the absence of proven curative therapies for Covid-19”.
Recourse to the infectious challenge would therefore not be necessary, because although animal models are imperfect, they already make it possible to test the effectiveness of vaccines. But that’s not all: the fact of testing these vaccines on young and healthy people would not make it possible to know their effectiveness on the rest of the population, made up of older and vulnerable people.