One or two doses? This is the question that comes to us from England. On Wednesday, the British decided to change their vaccination strategy, under the double pressure of a new variant of the much more contagious virus and a limited number of doses of the BioNTech-Pfizer messenger RNA vaccine.
Instead of giving two injections three weeks apart, as per the initial protocol, the English authorities have decided to separate the two administrations up to twelve weeks. Objective: to vaccinate more people with a single dose, while waiting for new deliveries of the vaccine to make the second injection. Their reasoning: a single dose already provides protection, even if it does not become optimal until the second injection.
Pfizer BioNTech has warned against this change of foot. For the laboratory, there are no data to guarantee protection beyond 21 days with a single injection. He recalls that even if a first protection occurs twelve days after the first injection, two doses of vaccines, spaced three weeks apart, are necessary to obtain an effectiveness of 95%. This is the only protocol that has shown its merit in phase 3 trials, he insists.
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A choice that is debated
This decision is the subject of debate across the Channel, between supporters of “war medicine” to deal with emergencies, and scientists who warn of the risks of not following the protocol, in particular to prolong immunity, and make it really effective in the elderly. The controversy is also mounting in England over logistics: delaying the second dose means deprogramming appointments of elderly people who have already had their first to schedule others. With the consequence of the uncertainty that all of them will return many weeks later for their last injection, making the promised protection even more uncertain …
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In France, where Olivier Véran has promised to speed up the vaccination schedule, the debate is not relevant for the moment. Jean-Daniel Lelièvre, head of the immunology service at Henri Mondor hospital and expert at the HAS, believes that there is currently no solid scientific data to justify the British turn. It was however mentioned by the chairman of the German vaccination commission, Thomas Mertens. With a principle of reality: managing the shortage of vaccines. Pfizer said on Friday it would step up production. But the laboratory expects likely supply disruptions until other vaccines are available in the European Union.
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What do we know about the South African variant?
Code name: “501.V2”. The new variant of the coronavirus, detected for the first time in France this Thursday, comes from South Africa. After the new British strain, which worries about its greater contagiousness, the South African variant is closely followed by European authorities. Information concerning it is still fragmentary, but it has spread very quickly in South Africa, to the point of making it the state most affected by the epidemic on the African continent. The country has passed one million people infected and 28,469 deaths. The variant is different from the new strain detected in Great Britain. Do its mutations create more serious forms of the disease? Impossible to say today. Is it more contagious? The question gave rise to a pass of arms between the English Minister of Health and his South African counterpart. Yes, according to the Briton who considered this new form of virus at the end of December “highly worrying”. “There is no evidence that the South African strain is more pathogenic than the British strain,” replied the South African Minister of Health in return on December 25.
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