Will a decision on a few milliliters of product upset part of the vaccination strategy against Covid-19?
Pfizer, which previously considered that five doses could be extracted from each vial of its vaccine, now considers that six can be extracted.
A decision that worries many doctors in more than one way: it is now mandatory to extract this sixth dose, a technical gesture that only a few doctors were used to doing, and, above all, we will have to keep the pace planned with stocks of bottles delivered to France which will be smaller.
Explanations.
Why did Pfizer make this decision?
On Wednesday, the Directorate General of Health told the medical news agency APM News that Pfizer considered since Monday that the vials of its vaccine developed with the German firm BioNTech were designed for six injections.
The group says it complies with the opinion of the European Medicines Agency.
On January 8, it had "recommended" to consider that each vial now made it possible to manufacture six doses.
Until then, it was planned to make "only" five each time.
Concretely, a vial contains 0.45 ml of product.
This should be diluted in 1.8 ml of sodium chloride solution for injection.
The whole then forms a little more than 2.2 ml of solution.
Using a syringe, the healthcare professional then collects 0.3 ml each time to constitute a dose, to be injected into the patient's arm.
In theory, therefore, a vial could allow six or even seven injections.
“Seven doses is imaginable on paper but infeasible in practice.
There are always drops on the wall or which remain in addition in the syringe ", indicates to the Parisian the doctor at the geriatrics pole of the hospital center of Cannes, Laurent Fignon, who began this week the second injections on the patients.
On the other hand, many professionals were already able to manufacture six doses, and therefore to vaccinate more people than initially planned.
What will this change?
From now on, these “vaccinators” will no longer have a “bonus dose”, to use the expression of general practitioner Jérôme Marty.
"We will have much less room for maneuver, we will have to be very attentive at the time of the manipulations and it will take a lot more time", squeals the president of the union French Union for a free medicine (UFML), one of the first to sound the alarm on Wednesday evening.
#PfizerBioNTech doesn't give a damn about our face ...
You know that field doctors have highlighted the fact that we could, with suitable equipment and a protocolized technique, take 6 doses from a bottle (announced to 5)
Well The laboratory reacted: pic.twitter.com/BMfSt1yB3e
- DrMartyUFML-S (@Drmartyufml) January 20, 2021
Laurent Fignon wants to be more reassuring.
"Sometimes you have to leave the bottle still for a few minutes so that all the drops fall to the bottom, but it is largely doable, especially in hospitals with professionals accustomed to this kind of gesture," he says.
This can potentially be more of a concern for others, who were still used to five doses per vial.
The question of hardware is also likely to pose a problem.
To limit losses when extracting the doses, caregivers will have to use a syringe with a crimped needle, so that it has a low "dead space".
This is the volume of liquid remaining after the syringe plunger is fully depressed.
And to be able to make six doses without problem, every tenth of a milliliter is good to keep.
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However, several doctors say they have not yet received this adapted material.
“Some have received syringes with a needle with too large a diameter or with a cap that creates too much dead volume,” says Jérôme Marty.
Laurent Fignon, for his part, is "reassured" to have learned from the pharmacy of the CHU de Nice, this Friday morning, that new needles had been received.
"The marketing authorization now provides for six doses per vial, for the countries to provide the equipment," he says.
The new syringes received in Nice./DR
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This "medical gesture" to be performed with appropriate equipment in syringes constitutes "a real challenge", had also recognized the Ministry of Health during a situation update on Tuesday.
Contacted, the Directorate General of Health did not answer our questions at the time of publication of this article.
What are the consequences for deliveries?
Ultimately, the big winner in this story may well be the Pfizer laboratory.
Because who officially says six doses per bottle instead of five, says fewer vials to deliver, even though the group announced late deliveries last week.
"We will keep our delivery commitments to states in accordance with the orders that have been placed - these have always been based on a total number of doses, not vials - and in accordance with the labeling approved in each country," said indicated the manufacturer in an e-mail sent to AFP.
Clearly, if a country had ordered 300,000 doses, it had so far received 60,000 vials.
From now on, only 50,000 vials will be provided.
"The fact that there is room for maneuver is a good thing, I do not find it normal for this to change along the way", squeaks microbiologist Patrick Berche, member of the Academy of Medicine.