After the authorization of Johnson & Johnson’s single-dose vaccine against Covid-19 in the European Union on Thursday, the scientific director of the American company, Paul Stoffels, details to AFP “the secret boot” which he believes makes this very effective vaccine.
Why is this vaccine an important tool in the fight against the pandemic?
The vaccine that the European authorities have just approved is the first vaccine that has been studied on a very large scale (around 40,000 people) including on variants.
In addition, it is a single dose vaccine that remains stable when transported at a temperature of between 2 and 8 degrees Celsius, a standard refrigeration temperature, which will help facilitate large-scale implementation around the world.
What is your response to critics who claim that J & J’s vaccine does not protect as well as those of Pfizer and Moderna?
We conducted our study globally, on three continents: the United States, South America, and South Africa, in very difficult circumstances of the peak epidemic.
We now know how well the vaccine works on the variants, and we can show that regardless of region, variant or age, you are protected against severe forms of illness, hospitalization and death.
This protection is 85% for severe forms, and even 100% against hospitalization and death, so far we have not seen any (in people vaccinated). This is the most important challenge in this pandemic.
J & J’s vaccine is a viral vector vaccine, which uses another virus as a “vehicle”. What is the advantage of this approach?
We have a very good response in terms of antibodies, but cellular immunity is the one that makes (protection) durable, and also gives it a wide capacity for action.
The secret boot of this vaccine is the combination of the two.
Can you explain in simple terms what cellular immunity is?
When you are vaccinated as a child, vaccines protect you for life. So your body memorizes the pathogen, the agent that causes disease.
Even if for many of them, you will no longer measure the presence of antibodies over time, your body can still react because it immediately says to itself: “This is a pathogen that I have seen before”. And this is where cellular immunity is very important, both for immediate effectiveness but also to remember it for a long time.
Where are your trials on children and pregnant women?
At the moment, we are studying the vaccine in adolescents aged 12 to 17, it is underway. Phases 2 and 3 (when the efficacy study begins, editor’s note) for children under 12 will begin in April. Trials on pregnant women will begin now.
Are you going to do a specific vaccine against the variants?
As a precaution, we have already started to make a vaccine from the South African variant. We don’t know if we’ll need it, but if it does, it’s underway.
Some scientists worry that the body can recognize the mildly virulent “carrier” virus if injected a second time, and therefore eliminate it before it can trigger an immune response. Is this a problem for a possible recall for example?
In our work on HIV, we expose people to the vector virus four times in a year. Although we observed small changes, we did not see the inability to use it for a second dose.
Ad26 (Adenovirus 26) as vector, the one we use, was selected for its low immunogenicity (ability to trigger an immune reaction, editor’s note), as well as its low presence in humans. We are reasonably comfortable with the idea of doing a trouble-free recall.
Anything else we should know?
We have a very complete (production) network internationally, in order to ensure that we can serve the whole world, as well as a collaboration with Covax (device intended for disadvantaged countries, editor’s note).
We hope that very soon, after what we are doing in the United States and in Europe, we can move forward to vaccinate the whole world. And we have a big commitment at J&J to do it at cost (no profit).