New Covid vaccines: how they work – Actu Orange

posted on Tuesday, September 20, 2022 at 5:29 pm.

New Covid-19 vaccines are beginning to be authorized around the world, including on Tuesday by French health authorities. How do they work, who makes them? Update on these new serums.

– Adaptation to virus development:

The virus of the disease Covid-19, SARS-CoV-2, has the ability to mutate, just like other viruses. It’s a natural mechanism: viruses multiply and random genetic modifications can occur as their DNA replicates.

The first vaccines were developed from the original strain known as Wuhan. Since then, other variants have appeared, such as Delta or Omicron. The latter actually represents a family of variants, of which there are currently several sub-lines such as the BA.1.

The Omicron and its sub-variants were dominant throughout 2022, quickly replacing the previous Alpha and Delta variants. Today it is essentially a sub-variant of the Omicron BA.5 that dominates in Europe and the United States. To better respond to these mutations, pharmaceutical groups are adapting their vaccines.

A concept that is not new: in the case of influenza vaccination, for example, quadrivalent vaccines are used – developed with components from two strains of influenza A and two influenza B viruses.

– bivalent vaccines:

In the case of Covid, the so-called bivalent vaccines are intended for the same purpose: to teach the immune system to recognize several invaders. The American-German tandem Pfizer-BioNtech thus modified its first vaccine (Comirnaty) against the Wuhan strain for the arrival of Omicron. It now offers a booster dose of the bivalent vaccine “Omicron BA.1”, which contains both the messenger RNA (mRNA) of the original SARS-CoV-2 virus and the messenger RNA specific for the Omicron BA variant.

This serum was approved by the European Medicines Agency at the beginning of September. Hundreds of millions of doses will be ready this year, Pfizer says.

Spikevax, a vaccine from the US biotech company Moderna, has also been adapted as a bivalent vaccine against BA.1 on the same principle as Pfizer. This “Original/Omicron BA.1” serum was approved in Canada and also by the European Medicines Agency in early September.

In addition to Moderna and Pfizer/BioNTech, other bivalent vaccines are in the pipeline. This is especially the case with vaccine candidates from French and British laboratories Sanofi and GSK targeting the Delta and Beta strains.

– Arrival of BA.4 and BA.5 subvariants:

Laboratories are working on other bivalent vaccines, specifically targeting the Omicron, BA.4 and BA.5 subvariants that have become dominant in addition to the original strain.

In Europe, Pfizer and BioNTech have the lead. At the end of August, they received emergency approval from the FDA for their bivalent vaccine against BA.4 and BA.5.

They also received the green light from the European Medicines Agency on September 12.

Moderna has also developed a bivalent vaccine targeting BA.4/5: this is currently only approved in the United States, not yet in the European Union. However, Moderna explains that its Spikevax bivalent anti-BA.1 serum “shows (…) also a higher response against the Omicron BA.4/5 sublines” compared to the first-generation vaccine.

But in the absence of full clinical data, Professor Antoine Flahaut, director of the Institute of Global Health at the University of Geneva, says he is cautious about the “superiority” of the new bivalent vaccines compared to the first formulas.

– What vaccines for the autumn campaign?

In France, health authorities on Tuesday recommended the use of the Pfizer / BioNTech and Moderna bivalent vaccines in view of the autumn vaccination campaign. In conjunction with the flu measure, it would focus on people most at risk of developing severe forms of Covid-19, their relatives and certain professions in the medical-social sector, particularly exposed to the virus.

These vaccines, of which the country has already ordered several million, should be quickly available in vaccination centers and pharmacies.

Orders from Sanofi (monovalent beta) and Spain’s Hipra (bivalent alpha-beta), whose vaccines are still being studied by the European Medicines Agency, have also been placed but are not expected before the end of the year. General Directorate of Health.

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