The health authorities recommend that the second injection be 6 weeks apart

From three to six weeks: this period between the injection of the two doses of vaccines constitutes a “reasonable” alternative, assures this Saturday the High Authority of Health (HAS), to protect the most vulnerable and meet “epidemic outbreaks”.

“In the context of limiting the number of vaccine doses and to allow an increase in vaccination coverage for the most vulnerable in the short term, the extension of the time between two vaccine doses is an option to consider,” HAS indicates.

The World Health Organization, the National Medicines Safety Agency (ANSM) and Public Health France have already issued a statement on this.

A “limited” loss of efficiency

The vaccination schedule that has been followed so far is the administration of two doses at least 21 days apart for the Pfizer-BioNTech vaccine and 28 days for the one produced by Moderna. The extension of the injection time for the two doses would make it possible to “accelerate the administration of the first dose to the most vulnerable people”, ie, according to estimates by HAS, at least 700,000 additional people “who will be protected by the vaccine” the first the month of application of this measure.

At the individual level, the “risk of loss of effect” of the vaccine between two doses seems “limited”, HAS indicates.

The results of Phase 3 clinical trials for messenger RNA vaccines “show the effect of the Comirnaty® vaccine from Pfizer BioNtech starting from the 12th day after the first dose and that of the Moderna vaccine from the 14th day after the first dose.” she then explains that the oldest vaccinated people show “a satisfactory immunological response and vaccine effect like that found in the youngest.”

Three conditions to respect

However, for such a measure of the distance between vaccine doses to speed up vaccination coverage and slow down the circulation of the virus, the High Authority believes that three conditions must be met.

The first: vaccinate those most at risk in order of priority, namely those who are 75 years and older, then “those aged 65 to 74 years, starting with those with comorbidities”, and therefore more deaths related to Covid.

Secondly, the implementation of this modification of the vaccination plan must be “rapid”.

Third, “all available doses of the two vaccines” must be used and “vaccine capacity included, during potential containment periods” must be maintained.

High authority is also working on new indications for saliva samples, which are currently recommended for people with symptoms. These tests, much less invasive than nasopharyngeal swabs, can be extended to include asymptomatic humans.