The English will therefore shoot first. In the global race for the vaccine against Covid-19, the British authorities are preparing to announce the launch of the first “human infectious challenge”, a method which consists in inoculating the virus into healthy subjects to whom we have previously administered an experimental vaccine in order to observe the effectiveness of the protection.
Revealed by the Financial Times, the information has not been officially confirmed by the British Health Products Regulatory Agency (MHRA), but the various actors involved evoke an imminent agreement and welcome this step forward. Conversely, voices are raised against a method that is discussed, both from a scientific and ethical point of view.
This practice offers a major advantage: it makes it possible to shorten and simplify the long process of testing vaccines, in particular in its final phase of clinical trial, phase 3. During this phase, tens of thousands of volunteers are given a vaccine candidate, before being sent home. After several months, their state of health is compared to that of a control group who received a placebo. Have they been immune to the disease? Were they better protected against his symptoms? Have they developed any side effects? The procedure is long, expensive, and uncertain, especially if the prevalence of the virus remains limited.
Deliberate infection of volunteers
The infectious challenge makes it possible to reduce the number of volunteers and to reduce the duration of observation. The British trial thus plans to recruit 100 to 200 people. They will receive a vaccine candidate before being, one month later, voluntarily infected with the virus. No more chance: the effectiveness is measured in a few weeks. It was with such a process that the Briton Edward Jenner invented vaccination in 1797. More recently, the method has been used in the search for vaccines or treatments against typhoid, cholera or malaria.
But this voluntary infection of healthy subjects poses serious problems. First, find guinea pigs ready to contract the virus. This difficulty was lifted by the American organization 1 Day Sooner. For months she has been campaigning in favor of this method, she has received the agreement of more than 38,000 volunteers, including 2,000 British, to submit their bodies to such a protocol. In a press release, the organization has moreover “Greeted the British government” for his decision.
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