Does Moderna’s vaccine have “three times more mRNA” than Pfizer’s vaccine? – LCI

They are described as “twin brothers” by the Ministry of Health. According to health authorities, the vaccines marketed by Moderna and Pfizer to fight Covid-19 are “alike”, to use the terms used by Olivier Véran on Friday December 3 on Franceinfo. According to the Minister of Health, “the only difference” between the two products “is that if you are under 30, we prefer to give you Pfizer rather than Moderna”.

An explanation that does not satisfy Internet users. For several days on social networks, they have been highlighting the differences between these two products, criticizing in particular that of the American company, considered less safe. In question according to them, Spikevax (Moderna) would count “three times more messenger RNA”, the technology used by the two laboratories, than its competitor Comirnaty (Pfizer). What is it really?

If the health authorities think that the two products are almost similar, it is because they “are based on the same technology” and “exhibit comparable effectiveness”, as stated in site from the Ministry of Health. Except that twins don’t mean identical. It is true that certain differences exist, in particular on the dosage. An injection of Moderna’s product thus involves 100 micrograms (µg) of mRNA per 0.5 ml of saline solution. With Pfizer, the patient receives 30 µg in one dose 0.3 ml, after dilution. In the first case, the dosage is indeed three times stronger.

What does that mean ? Asked about the question, Professor Alain Fischer, Chairman of the Vaccine Strategy Steering Committee, acknowledged on LCI than “this dose a little higher” was “probably, but without absolute certainty” linked to a “very small risk in young people under 30 of an inflammatory complication”. As a reminder, these complications are not considered serious, and “pass after two or three days”.

An mRNA concentration possibly linked to more undesirable effects … but also to greater efficiency! Several studies have indeed shown since the beginning of the autumn that the American product would allow it to be protected for longer. British study (not yet peer reviewed) suggests, for example, that the Moderna vaccine would be the only one to be more than 90% effective several weeks after the second dose, unlike Pfizer and AstraZeneca.

In an opinion issued on November 8, the High Authority for Health therefore observed that “several studies carried out under real conditions of use tend to show a slightly higher vaccine efficacy for Spikevax compared to Comirnaty”. Enough to “to reinforce the interest of Spikevax, in particular in people at risk of severe form of Covid-19”.

The prohibition of this product among those under 30 is therefore the result of a fairly standard “benefit-risk” calculation. This does not mean that the vaccine marketed by Moderna “involves any particular danger”, as Alain Fischer recalled.

Moreover, for the most reluctant, it is important to underline that during the injection of the “booster”, it is a half-dose of Moderna which is injected. That is, 50 µg only. What to raise doubts about this weapon that we will need in the fight against the epidemic.

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