Covid-19: what do we know about the dosing errors that punctuated the vaccination campaign?

Covid-19: what do we know about the dosing errors that punctuated the vaccination campaign?
Covid-19: what do we know about the dosing errors that punctuated the vaccination campaign?

COUACS – Dosage errors that occurred in two vaccination centers in France were reported last Thursday. These incidents are not the first of their kind since the start of the vaccination campaign.

Audrey LE GUELLEC – 2021-05-31T19:31:22.045+02:00

If nothing links these two incidents which were reported in distinct regions of France, they gave rise to the same preventive measures. The local press echoed at the end of the week errors that occurred in the vaccine dilution process that led vaccination centers in Hautes-Pyrénées and Vendée to recall hundreds of patients for checks.

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These hiccups are not the first to give lead to the vaccination campaign. How to explain them? Do they have consequences for the people concerned? We take stock of the examples previously identified in France and abroad.

Where were these dosing errors found?

467 people who received a vaccine injection were recalled by the Lourdes vaccination center and the Regional Health Agency (ARS) following an error in the vaccine dose dilution process that occurred on May 22, a reported Thursday La Dépêche du Midi. “A vial was inadvertently diluted twice, resulting in the injection of a largely diluted vaccine”, detailed to the daily officials of the vaccination center of Lourdes. Also Thursday, a similar error related to the dosage was reported in Vendée, reports our colleagues from Vendée courier. It occurred at the Noirmoutier vaccination center on May 10 and this time concerned 200 patients.

These two recent examples are not the first to date. From April, 140 inhabitants of Epernay (Marne) were victims of this quack, just like fifty people in Châtillon (Hauts-de-Seine) a few days later.

More recently, the same error was repeated in Saint-Céré in the Lot, 91 patients having been contacted again after their injection. That is, according to these examples, at least nearly 1000 patients concerned since the launch of the vaccination campaign.

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And abroad ? Dosage errors have also occurred outside our borders. And this from the launch of the various campaigns within the European Union, since in December 2020, eight employees of a German retirement home were mistakenly administered five doses of vaccine. A few weeks ago, at the beginning of May, a 23-year-old Italian student was also injected with the entire contents of a vial of Pfizer-BioNTech vaccine, the equivalent of four individual doses, which must also be injected. be normally diluted with physiological saline. The young woman, in good health, still had to stay in the hospital and will be the subject of regular examinations over the coming months.

How to explain these dosing errors?

Usually, it is at the end of the day that doctors realize that an error has occurred, when a vial remains unused while appointments have been made. “The vials are counted every morning and afternoon, to ensure that they correspond to the number of patients called that day”, confirms with the Vendée courier Cyrille Vartanian, referent of the Noirmoutier vaccination center. Indeed, on May 10, at the end of the day, there was still a vial of Pfizer-BioNTech that had not been used, or the equivalent of seven vaccinations, so seven patients.

However, contrary to what applies to the serums of AstraZeneca, Moderna and Janssen, the content of the Pfizer-BioNTech must be diluted, at a rate of 1.8 ml of an injectable solution of sodium chloride (physiological serum) per vial. . And it is normally with the help of other syringes that a certain dosage of the mixed product (0.3 ml) is collected for administration to the patients. “The only possibility that I see, if we are not careful enough, is that we inject physiological serum into an empty bottle from which we have already extracted Pfizer doses before”, analysis Luc Duquesnel, coordinator of vaccination centers in Mayenne with the Parisian. “No other solution possible” neither according to Dr. Jean-Michel Caille L’Etienne. In other words, only serum is in this case recovered during the second step.

If the health authorities have each time remained evasive on the circumstances in which these errors occurred, each incident was an opportunity to make some reminders likely to reassure the French. Regarding the example of Epernay, “an analysis of the causes which led to this error was carried out” the day after the events, had thus reassured a press release from the University Hospital of Reims. “In order to secure the vaccination process, a health executive has been commissioned to strengthen the pre-existing procedures”, added the document.

What consequences for patients?

Each time this error occurred, the patients concerned were quickly contacted by the vaccination center or directly by the ARS, so that they could be offered a new appointment. “I reported an adverse event to the ARS (Regional Health Agency, editor’s note)”, details with our colleagues Cyrille Vartanian. “And a decision was taken, in consultation with those in charge of vaccination at the CHD (Departmental hospital center in La Roche-sur-Yon), to recontact the 200 people who had received an injection on the afternoon of May 10.”

In its press release in April, the Reims University Hospital insisted on the fact that this contact went beyond making a new appointment. “During this call, they (the patients) had the opportunity to talk to a doctor to answer their questions”, it was specified.

Receiving physiological serum, that is, a simple saline solution, presents no danger to the body, the real risk being that the people concerned may think they are wrongly protected. The latter being difficult to identify, a serological examination is offered in case of doubt to the suspect group to verify the status of each person’s vaccination coverage and thus identify patients who have not been immunized at all.

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