“At the individual level, the three-dose regimen is probably the most relevant regimen” against Covid-19, said Saturday, November 6 on franceinfo Jean-Daniel Lelièvre, head of the infectious diseases department at the Henri Mondor Hospital in Créteil, vaccination specialist and expert at the High Authority of Health and with the WHO, after government spokesman Gabriel Attal said Friday, November 5 that the idea of a third dose of vaccine “made its way” within the executive. The two-dose regimen “is an emergency scheme”, recalls Jean-Daniel Lelièvre. And the third dose will allow you to have “a protection that will be different and more powerful”.
franceinfo: What is the use of this third dose of vaccine? From how many antibodies are we protected against severe forms of Covid-19?
Jean-Daniel Lelièvre: What we call the correlates of protection, that is to say the level of antibodies that will truly protect you against severe forms, are not fully defined. We have some ideas, obviously. This is a subject on which the international community has been working hard for several months. But it’s quite difficult to define it. We already have answers on the clinical part, that is to say on the reappearance of Covid diseases in people who had been vaccinated with two doses. And over time, we see the reappearance of these infections which are the reason why we are currently proposing a third dose.
Isn’t it more interesting to do a serology to know your antibody level before doing your third dose?
No, because it is not completely predictive of protection. Obviously if you have very high antibody levels you may be protected. But be careful, even if these antibody levels are very high, they are not necessarily relevant or effective in protecting you against Sars-Cov2 variants. If you were vaccinated a very long time ago, there has not been what is called sufficient maturation of some of your cells, called memory B cells. And if you do a vaccine booster, you will stimulate these cells that are a bit special. You will end up with an antibody level which will be higher, but which, in addition, will allow you to be much more active against the delta variant. So simple serology is not the most effective parameter to predict protection against disease. If you do a third dose of the vaccine, you will get protection which is going to be different and more potent than with two doses. And the optimal vaccination schedule is likely to be a three-dose schedule and not a two-dose schedule. It should be understood that the two-dose regimen is an emergency regimen which aimed to prevent infections in a very important way in the whole population. But at the individual level, the three-dose regimen is probably the most relevant regimen.
Do you think that the French population is ready today to submit to new restrictions and to this third dose of vaccine which will eventually condition a health pass?
I think we must all keep in mind that, in the past, the only possibility that we had to block the epidemic waves when they were present, was to carry out containment. And we can clearly see the difficulties and the major consequences that this confinement had, both on our economic life, but also on our everyday life. It has been a factor in major psychological disturbances for a large number of people in this country, especially children. To avoid all this, you need to have the best possible immunization coverage. And we must be able to respect the barrier gestures whenever it is going to be important. All this will prevent us tomorrow from further drastic measures, as has been the case in other countries of the world. If we don’t, we will be forced to confine. So there are other countries which have not confined and which have not had the same problems as us. But the countries that did not resort to containment were countries with a population density that was completely different from ours. So you absolutely must not compare yourself to others. And once again, we can clearly see the relevance of vaccination and distancing measures. Let’s continue down this path to avoid the worst tomorrow.