Two of the main anti-Covid treatments, Evusheld and Ronapreve, lose effectiveness against infections with the Omicron variant, but this reduction is much less marked compared to its BA.2 version, shows a study relayed on Monday April 4 by the Institut Pasteur.
Read alsoVaccines suitable for Omicron not available before “autumn”, according to Berlin
“
The clinical efficacy of these treatments against Omicron infection is (…) probably less good than against Delta
”, the previous dominant variant, summarized researcher Olivier Schwartz, who co-directed this study, in a press release.
This work, published at the end of March in the journal Nature Medicine, looked at the ability of two treatments, Ronapreve and Evusheld, to act against infection with the Omicron variant, which has become widely dominant in the world since the end of 2021.
“Reduced” neutralizing activity
These treatments, respectively developed by the Roche and AstraZeneca laboratories, are synthetic antibodies.
Both are used preventively in patients who cannot be vaccinated, although Ronapreve is also used as a curative treatment.
The arrival of Omicron has changed the game because its profile raises fears that it is more resistant to these treatments.
To be sure, the researchers measured in the laboratory how resistant this variant was in the blood of around thirty patients receiving these treatments.
"
The neutralizing activity of Ronapreve against Omicron, and to a lesser extent that of Evusheld, is reduced in these patients
", concludes this study.
This decline is much less marked against Omicron's BA.2 sub-variant, however, than against BA.1, its first incarnation to be primarily released.
However, BA.2 currently seems able to take precedence over its big brother.
This study is based on in vitro work, which limits the conclusions to be drawn in real life.
However, the researchers report a few infections, one of which was serious, in the patients observed, which suggests that the treatments lose clinical efficacy, even if the sample observed is very small.
Read alsoCovid-19: why China, caught up in the virus, refuses to abandon its “
zero Covid
” strategy
Several health authorities, as in France, had in any case practically given up the use of Ronapreve, whose fall in effectiveness was already hardly in doubt.
On the other hand, the situation is more complex with Evusheld, which still seems likely to confer satisfactory protection against Omicron, in particular BA.2.
At the end of March, the day after the publication of this study, the French drug authority, the ANSM, decided to modify its recommendations on Evusheld.
She now recommends a higher first dose, in the idea that this can compensate for the loss of effectiveness against Omicron.
