Hard blow for the vaccination campaign against Covid-19 in France?
After the woes of AstraZeneca, it is the turn of the other adenovirus vaccine, Janssen, to be in turmoil.
In question: a large number of vaccine failures and an over-representation of patients vaccinated with this product among those in intensive care.
These are the elements relayed by the National Medicines Safety Agency (ANSM) in its latest pharmacovigilance report, published on Monday.
"Investigations are underway," said the agency, while a million French people have been vaccinated with Janssen.
We take stock.
What does the ANSM say?
In pharmacovigilance, we speak of a new “potential signal”.
People vaccinated with Janssen would be much less protected than hoped, probably in part because they only received one dose.
This was also one of the main advantages of this vaccine: presented as a single dose, it offered in theory the guarantee of being "cleared" once the first injection had been received.
In detail, the ANSM noted 32 cases of vaccine failure, including 29 "serious" and 4 deaths.
These episodes occurred between 3 and almost 18 weeks after the bite.
It should be noted that 25 of the 27 patients whose antecedents were known presented at least one pathology at risk of serious form (diabetes, obesity, pulmonary disease, etc.).
Read also "It's a shame": why the Janssen vaccine against Covid-19 "did not find its audience"
Two regional pharmacovigilance centers (CRPV) have also noted an “over-representation” of patients vaccinated with Janssen among those fully vaccinated and hospitalized in intensive care: 4 out of 7 in Marseille and 3 out of 6 in Tours.
However, this vaccine was used in much smaller proportions.
“These are not large numbers and all these patients had comorbidities, but this constitutes an alert,” notes Marc Léone, head of the anesthesia and intensive care unit at the North Hospital of Marseille.
Why do we find out so late?
On the one hand, the Janssen vaccine is the latest arrival of the 4 vaccines administered in France and it has only been used since the end of April, ie 4 and a half months ago. Then, "to have infections and hospitalizations for Covid, the virus must circulate with a risky exposure", reminds the Parisian Joëlle Micallef-Roll, director of the regional pharmacovigilance center of Marseille. However, the epidemic was in sharp decline at the end of spring and the fourth wave, particularly strong in the Bouches-du-Rhône, did not begin until July. It is therefore especially in August that the cases of vaccine failures with Janssen were observed in hospital departments.
Many studies also suggest that the effectiveness of vaccines wanes over time.
This makes the risk of vaccine failure more likely after several months, especially since Janssen starts from lower than Pfizer and Moderna: 67% efficacy against moderate to severe forms (according to the results of clinical trials), compared to over 90% for messenger RNA vaccines.
The Delta variant, the majority in France since the end of June, could also have contributed to reducing the protection conferred by vaccines.
“The efficacy may have dropped to around 40% and the field data shows that a single dose of Janssen vaccine is not enough.
This does not call into question its usefulness, but suggests that action must be taken if we want to maintain good efficiency, ”Joëlle Micallef-Roll analyzes.
It is also possible that not all cases of vaccine failure have been reported.
On August 3, the Directorate General of Health sent health professionals a message reminding them to report serious cases to regional pharmacovigilance centers.
However, 84% of vaccine failures with Janssen were reported after August 3.
What consequences for patients?
One million people have been vaccinated with Janssen since the start of the campaign in France. The experts contacted are unanimous: there is "no particular concern" for them. "We realize that a single dose is not enough and we have a solution to remedy it", emphasizes Joëlle Micallef-Roll. This solution is a booster dose of messenger RNA vaccine (Pfizer or Moderna indifferently) at least 4 weeks after vaccination with Janssen, as the High Health Authority recommended at the end of August. In a way, the ANSM report only confirms and reinforces this need. “As soon as we have been vaccinated with Janssen, if it is at least 4 weeks old, you need an additional dose,” insists the Ministry of Health.
Until then, it is anyway recommended to continue to respect barrier gestures, even if you are vaccinated.
"People overreact directly while in science we need time, and we adapt," sighs Marc Léone, tired of hearing some people speak of "error" not to have administered two doses from the start. .
Except that it was not possible to do otherwise, the marketing authorization having been granted for a single-dose regimen (the only one for which data were available).
What about the Janssen vaccine in France?
Only people aged at least 55 years can be vaccinated with Janssen, due to a slightly less positive benefit / risk balance in younger people.
But this vaccine is hardly ever administered in France, since there are barely a thousand doses administered each day.
Read also Covid-19 vaccines: why are there "incompressible" losses?
However, the laboratory has just resumed deliveries after several weeks of suspension, said the Ministry of Health on Tuesday.
350,000 doses are expected this week, then 450,000 each week in the short term.
"The target of over 55s has already been highly vaccinated for a while," we point out to the government, without detailing what will happen to these stocks.
They could be supplied to foreign countries via the Covax device.
At the end of July, Tunisia, for example, received 500,000 doses of Janssen vaccine from France.
