Home » Sometimes they come back: protein-based vaccines are back. But how effective are they?

Sometimes they come back: protein-based vaccines are back. But how effective are they?

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Sometimes they come back: protein-based vaccines are back.  But how effective are they?

The pandemic, at least for now, is slowing down but doctors and institutions do not stop reiterating how important it is to continue immunizing also because new vaccines are on the way. In addition to the bivalents and those updated against the new variants, protein ones are expected shortly. How do they work? How do they differ from those in mRna and above all how effective are they? We asked the virologist Fabrizio PregliascoProfessor of Hygiene at the State University of Milan.

A long story

Protein vaccines are the result of a long-proven technology and in fact are already used against diseases such as hepatitis, whooping cough, shingles and flu. “In this phase in which the anti-Covid vaccination will have to be routinely presumably no longer mandatory, but perhaps also recommended to the youngest and to those at risk, having different technologies and production capacities is very important”, underlines Pregliasco.

Fabrizio Pregliasco

How does it work

But what is the mechanism by which protein vaccines work? “By injecting specific, harmless proteins of a pathogen – replies Pregliasco – protein vaccines provide the immune system with instructions to identify the pathogen. When a vaccinated person comes into contact with the true pathogen, the antibodies can bind to the protein already known, preventing it from spreading in the body. So if an infection occurs, the immune system will remember how to quickly fight the pathogen. ” As a result, the person likely will not get sick or will only develop mild symptoms.

The difference compared to those in mRna

Unlike mRna vaccines that contain the genetic instructions to produce the spike protein, protein subunit vaccines are composed of ‘protein fragments’ of the virus that are produced using a technological platform already used for the production of other vaccines, such as influenza. .

“In the production of this type of anti-Covid-19 vaccine – explains the virologist – a portion of DNA that contains the information necessary to produce the spike protein is inserted into a baculovirus that will infect some cells in vitro that will release the material. genetic useful for the production of the spike protein “.

Graphics: General Secretariat of the Council of the European Union

Graphics: General Secretariat of the Council of the European Union

The latter is then extracted, purified and compacted to obtain viral nanoparticles that can contain up to 14 spikes. These particles, ‘reinforced’ by an adjuvant molecule, are thus ready to be injected into the human body to obtain the production of antibodies against the Sars-CoV-2 spike protein.

What protein vaccines are available

While Europe has chosen to go all-out on mRna vaccines, some countries, especially low-income ones like India, have used protein-based ones. But about two weeks ago, the Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) gave its okay to use the Covid-19 vaccine produced by the US Novavax (Nuvaxovid) as a dose of homologous and heterologous recall in adults from 18 years of age.

Once approved by the European Commission, Nuvaxovid will become the first protein subunit vaccine to be authorized in the EU for both primary and booster use, regardless of the primary vaccine used.

The CHMP’s recommendation is based on several clinical studies in which a single booster dose of Nuvaxovid was administered to healthy adult participants approximately six months after the two-dose Nuvaxovid primary course. The third dose produced an increase in immune responses comparable to or above the levels associated with protection in the phase 3 clinical trials.

In addition, in the Covboost study, Nuvaxovid induced a robust antibody response when used as a third heterologous booster dose. “But in the autumn – adds Pregliasco – the Sanofi protein vaccine will also arrive on which there are several clinical studies that highlight its effectiveness against the most problematic variants, including Omicron”.

Covid, the Omicron 4 and 5 subvariants are now the most contagious and aggressive

by Fabio Di Todaro


The new protein-based vaccine expected in the fall

Last June Sanofi announced that its next-generation, protein-based Covid-19 booster vaccine provides a strong immune response against the most problematic variants, including Omicron. The news is based on the results of two separate studies in which the booster vaccine used was modeled on the variant of the Beta virus instead of the original D614 virus (Wuhan).

“Clinical studies – says Pregliasco – show that the new protein vaccine formulated on the Beta variant, which contains three of the four main mutations that are normally observed in all the variants of concern that have emerged so far, has a good efficacy even on the latest variants”. Indeed, the Phase 3 immunogenicity and safety study showed a 15-fold increase in antibody titers against the original D614 virus and a 30-fold increase against the Beta strain. Specifically, against Omicron, preliminary data shows a 40-fold increase against BA.1.

Lo studio Coviboost

To confirm the effectiveness of this new vaccine is also an independent study called Coviboost and conducted byAssistance Publique Hôpitaux de Paris (APHP). In this study, Sanofi-GSK’s next-generation booster developed a stronger immune response than Pfizer BioNTech’s currently available booster. The percentage of patients with at least a 10-fold increase in neutralizing antibody titers for the original Sars-CoV-2 strain D614 between day 0 and day 15 was 76% for the next generation protein booster compared to 63 % for Pfizer BioNTech’s D614 booster.

The advantages

Always considered the ideal alternative for No Vax, these vaccines actually have not found particular sympathy in this segment of the population at the moment. How come? “Because in reality the element of genetics was only an excuse because in the narration of the No Vax the dominant idea is that Covid does not exist and therefore no vaccine is needed”, replies the virologist. So what are the advantages of this formulation? “No presence of wild viruses, use of a specific gene sequence, a large-scale production capacity because it is a ‘simple’ vaccine and also a storage method that requires a temperature ranging from 2 to 8 degrees”, replies Pregliasco.

Who is it suitable for and how long the protection lasts

Who are the new protein vaccines suitable for? “In reality, everyone, regardless of age and can be administered both as a first dose and as a booster”, replies Pregliasco who, as regards the duration of vaccination protection, points out: “The rip-off for all vaccines is linked to a peculiarity of Covid which it does not confer a protection for life and the fact that the variants follow each other with great speed as the virus seeks a way to continue its dirty work. This is why the vaccination fee in the future will be the element that will make coexistence better since Covid will continue to circulate with trends like those of a stone in the pond. The arrival of the new protein vaccine in the autumn will be an opportunity to relaunch the vaccination campaign at a time of the year when perhaps people will be more sensitive to the message “.

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