Sacred thorn in Moderna's side.
In quick succession Wednesday and Thursday, Sweden, Denmark, Norway and Finland announced that they now advise against using this vaccine against Covid-19 in adolescents or even in young adults under 30 years old.
Several of them have suspended it altogether for these age groups.
The reason ?
The risk of pericarditis and myocarditis, two inflammations in the heart - but impacting two different parts -, following the injection.
Why did these countries make this decision?
The health authorities say they are based on a Scandinavian study having "established that men injected with the Moderna vaccine and aged less than 30 years had a slightly increased risk of developing inflammation of the myocardium", explained Thursday Mika Salminen, director of the Finnish Institute for Health and Welfare (THL).
However, this data has not yet been published.
This should be the case within two weeks.
Read also Pfizer or Moderna vaccination: should we be concerned about cases of myocarditis and pericarditis?
In other words, it was under the "precautionary principle" that such decisions were taken, as the Swedish Public Health Agency (FHM) and an official from the Danish health authorities indicated.
In Sweden, just over 80,000 young people under 30 have received a first dose of Moderna and are awaiting the second.
Such an announcement is reminiscent of the similar one made by these same countries concerning the AstraZeneca vaccine last March.
At the time, it was the risk of thrombosis that was singled out.
But beware: these Scandinavian states have not completely suspended vaccination among young people.
On the contrary, they always recommend that they get immunized but with Pfizer, the other messenger RNA vaccine… yet concerned by the same signal.
What do we know about the risks with the Moderna vaccine?
The risk of myocarditis and pericarditis following Moderna vaccination has been known and well identified for several months. In its latest pharmacovigilance report, the National Medicines Safety Agency (ANSM) reports 79 serious cases of myocarditis and 56 of pericarditis in total, for a cumulative number of 10 million injections carried out (including 5.2 million first doses). 46 of these myocarditis and 15 of these pericarditis were observed in people under 30 years of age. And the vast majority of these serious cases have been identified since July 2, most often after the second dose.
As regards the specific case of adolescents aged 12 to 18 years, “to date and on still limited data, the cases of adverse events reported (…) do not present any particular characteristic compared to those reported for older subjects, ”the report reads. And the vast majority of these post-vaccination cardiac disorders are "restored or in the process of recovery", further indicates the ANSM.
In short: a "signal" does exist concerning Moderna and it "requires a more in-depth evaluation" especially among young men, the European Medicines Agency said in a report published on September 17th. “It seems logical to me to ask the question. Even if the benefit / risk ratio is positive, you have to think about how to minimize the risk. Half a dose for the youngest? The question also arises of the risk with three doses, ”suggests cardiologist Florian Zorès, who has been closely monitoring this subject for several months. The Pfizer vaccine is also affected by the same signal, without knowing whether the risk is greater or less than with Moderna.
Regarding this benefit / risk ratio precisely, the American Centers for Disease Control and Prevention (CDC) had justified their authorization of the Moderna vaccine in adolescents by the fact that the injections could cause a maximum of 70 cases of myocarditis ... but that 'they would prevent 5,700 infections, 215 hospitalizations and two deaths, reports The New York Times.
Several studies have also suggested that the risk of such heart problems is higher with infection than with vaccination, but there is a lack of consolidated data by age group.
“There is still a 20% drop in cardiac function in certain cohorts, admittedly transitory but which can be the bedrock of cardiac insufficiency,” observes Florian Zorès.
What could be the impact in France?
At this stage, no suspension of injections with Moderna in young people is envisaged by the government.
"Such a decision is not on the agenda in France", tells us the Ministry of Health, which will be based on the opinions of the scientific authorities (ANSM, EMA, Haute Autorité de Santé, etc.).
Read also Anti-Covid vaccination: more effective, more delivered ... Moderna, the comeback?
A decision similar to that taken by the Nordic countries would certainly have important consequences for the vaccination campaign in France.
Moderna is the second most widely used vaccine today, with one in four people injected for the first time daily.
It can also be used, indifferently from Pfizer, for booster injections in the elderly, frail, and caregivers, HAS said on Wednesday.
