BIVALENT VACCINE. Bivalent vaccines targeting the Omicron variant have been administered in France, as a booster dose, since October 2022. For WHO experts, the data on these vaccines are not sufficient to favor them over others.
[Mise à jour le 14 octobre 2022 à 15h51] A fall vaccination campaign with new Covid vaccines began on Monday October 3 in France. These vaccines have been authorized by the High Authority of Health after being validated by the European Medicines Agency (EMA) on September 1. A vaccine produced by Pfizer targets BA4 and BA5 sublineages of Omicron, the other from Moderna targets the BA1 variant (only for people over 30). They are called “bivalent“as they target the initial strain of Sars-Cov-2 (Wuhan) and the variant Omicron. For the WISE (Strategic Advisory Group of Experts on Immunization of WHO), “the data is not sufficient to favor them over others booster vaccines”. The monovalent vaccines used so far as a booster are as effective as the bivalent against the variants of Covid currently circulating, according to these experts. The important thing, they say, is to do a booster dose 4 to 6 months after the last to be protected. Who are the bivalent Covid vaccines intended for? In first vaccination? For the 3rd dose of vaccine? The 4th dose ? What is their efficiency ?
What are the new Covid 2022 vaccines?
The three new Covid vaccines authorized in France on September 19 by HAS and available from October 3 are versions of the Covid vaccines from the Pfizer and Moderna laboratories:
- Comirnaty Original/Omicron BA.1
- Comirnaty Original/Omicron BA.4-5
- Bivalent Spikevax Original/ Omicron BA.1.
For the vaccination campaign in France, the two vaccines used are Comirnaty Original/Omicron BA.4-5 and Spikevax Bivalent Original/Omicron BA.1 clarified the Directorate General of Health. These vaccines are adapted versions of the original Comirnaty vaccines (Pfizer/BioNTech) and Spikevax (Modern) for target Omicron’s BA1, BA4 and BA5 sublines in addition to the original SARS-CoV-2 strain. That’s why they say “bivalent“while the vaccines used in primary vaccination are said to be “monovalent” because they only target the original strain of the virus. The new vaccines have the same principle of action: each contains mRNA (messenger RNA) molecules who have instructions for make the spike proteins of SARS-CoV-2 original and of the Omicron BA.1 or BA4-BA5 sub-variant. The spike protein is a protein on the surface of the virus that the virus needs to enter body cells and may differ between variants of the virus. By adapting the vaccines, the objective is to broaden the protection against the different variants. When a person receives one of these vaccines, some of their cells read the mRNA instructions and temporarily produce the spike proteins. The person’s immune system then recognizes these proteins as foreign and activates natural defenses – antibodies and T lymphocytes – against them. If the vaccinated person later comes into contact with the virus, the immune system recognizes the spike protein on its surface and prepares to attack it. Antibodies and immune cells can protect against COVID-19 by working together to kill the virus, preventing its entry into body cells and destroying infected cells.
What is a bivalent vaccine?
A bivalent vaccine is a vaccine that has two valencies. A valence is the part of a vaccine corresponding to the protection against a single germ. A bivalent vaccine protects against 2 diseases or 2 germs causing the same disease. The bivalent Covid vaccines thus protect against the initial strain of the Sars-CoV-2 coronavirus and against the Omicron variant of this virus. We can also have “multivalent” vaccines which protect against several germs causing the same disease or against different diseases (like the MMR vaccine which protects against measles, mumps and rubella).
What is the name of the new Covid vaccines?
The Haute Autorité de Santé has designated the new vaccines under the names: Comirnaty Original/Omicron BA.1, Comirnaty Original/Omicron BA.4-5, Bivalent Spikevax Original/ Omicron BA.1.
What is Pfizer’s new Covid vaccine?
Two new vaccines developed by the American laboratory Pfizer-BioNTech target for one the BA.1 Omicron sub-lineage and for the other the BA4-BA5 sub-lineages. It is the one that targets BA4-BA5 that is used in France for the recall campaign launched in October. They are based on the original vaccine against Covid, Comirnaty (the most administered in France since 2020). They contain 15 µg of mRNA coding for the SARS-CoV-2 spike protein, which is present in the original Pfizer vaccine and 15 µg of mRNA coding for the protein spike of the Omicron BA.1 subvariant or BA4/BA5. Other than the addition of the spike protein mRNA sequence, all other components of the vaccine remain unchanged.
What is Moderna’s new Covid vaccine?
The new vaccine developed by the American laboratory Moderna targets the BA.1 Omicron sublineage and can only be administered to people over 30 years of age. It contains 25 µg of the currently authorized booster (Spikevax/mRNA-1273) and 25 µg of Omicron BA1 subvariant. A study has enabled its validation. She wore on more than 800 adults aged 18 and over. The study revealed that a booster dose of bivalent Spikevax Original/Omicron BA.1 induced a stronger immune response against SARS-CoV-2 strain and Omicron BA.1 subvariant compared to a booster dose of the original Spikevax vaccine.
Who should be vaccinated with the new Covid vaccines?
These new Covid vaccines are aimed at people at risk of severe forms of Covid. They are authorized in people aged 12 and over who have received at least one primary vaccination course against Covid-19, regardless of the vaccines used at the time. They are authorized only for a booster dose. The population groups to be targeted for this additional dose of vaccine according to HAS recommendations are:
- people over 60 and adults under 60 at risk of severe disease :
- those who have comorbidities that expose them to these severe forms,
- pregnant women, from the 1st trimester of their pregnancy,
- immunocompromised people regardless of age,
- children and adolescents at high risk suffering from pathologies justifying it.
- the entourage of these people (cocooning strategy) as well as the people who are in regular contact with them:
- professionals in the health and medico-social sector.
For people under 30HAS maintains its recommendation to only use Comirnaty® vaccines (Pfizer BioNTech).
When to do this new vaccine booster?
The booster dose should be administered:
- From 3 months after the last injection or infection for people aged 80 and over, as well as for residents of nursing homes and USLDs and severely immunocompromised people, regardless of their age;
- From 6 months after the last injection for all other eligible persons. In the event of recent infection with SARS-Cov2, the booster is recommended from 3 months after the infection, respecting a minimum period of 6 months after the last injection.
How effective against Omicron?
“The expected clinical efficacy for these new bivalent vaccines is at least equivalent or even superior to that of the original vaccines monovalent, without this probable superiority being able to be currently demonstrated in real life” indicated the HAS in its press release of September 20. An opinion nuanced by the WISE (Strategic Advisory Group of Experts on Immunization of WHO) on October 10 since he estimated that “the data are not sufficient to favor them (bivalent vaccine, editor’s note) over the others vaccines already used as a booster”. The monovalent vaccines used so far as a booster are as effective as the bivalents against the variants of Covid currently circulating, according to these experts. The important thing, they say, is to do a booster dose 4 to 6 months after the last to be protected.
What side effects?
The tolerance of these vaccines “is identical to that of monovalent vaccines” inform the HAS. Side effects observed with vaccines targeting Omicron were “comparable to those seen with the original vaccines and were generally mild and short-lived” indicates the EMA.
Sources
Highlights from the Meeting of the Strategic Advisory Group of Experts (SAGE) on Immunization – October 3-6, 2022.
Launch of the autumn vaccination campaign against Covid-19, September 28, 2022, DGS.
Covid-19: HAS includes bivalent vaccines in the vaccination strategy for the fall. Press release, September 20, 2022
ECDC-EMA statement on booster vaccination with Omicron adapted bivalent COVID-19 vaccines. EMA. September 6, 2022.
Pfizer and BioNTech Receive Positive CHMP Opinion for Omicron BA.1-Adapted Bivalent COVID-19 Vaccine Booster in European Union. Pfizer, September 1, 2022
EMA CHMP adopts positive opinion recommending authorization for the use of Moderna’s Omicron-Targeting Bivalent Booster in the European Union, Moderna, September 1, 2022.