To end the Covid-19, the hope of the nasal vaccine

To end the Covid-19, the hope of the nasal vaccine

HEALTH – On May 11, 2020, the French government began lifting containment, after the end of the 1st wave of Covid-19. Two years later, the fifth wave of coronavirus is in full decline, but the coronavirus pandemic is unfortunately far from over. The most recent example: South Africa, the first country affected by Omicron in November, saw its number of cases explode again with the austral winter.

It is in this context that the United States is organizing a second world summit on Covid-19 this Thursday, May 12. Objective: to allow “to redouble our collective efforts to end the acute phase of the pandemic and prepare for future health threats”, according to the White House.

If the vaccines have (very) greatly reduced the risk of a severe form of Covid-19, these have not made it possible to stop the transmission of the virus and, as a corollary, its mutations. To truly “end” the pandemic, above all, it would be necessary for the nations of the world to invest more clearly in another preventive treatment: the nasal or mucous vaccine.

“Several studies show that the classic vaccines, intramuscular, produce very few antibodies in the mucous membranes”, explains to the HuffPost the immunologist Morgane Bomsel. However, the mucous membranes (inside the nose, mouth, etc.), it is precisely through there that the virus enters the body… and comes out to infect other people. « This reinforces the idea that a mucosal vaccine could be much more effective than those by injection in reducing transmission, » said the researcher.

Block the gateway to the virus

Nasal vaccines are rare, but not new. There is also one for the flu, approved in Europe, the United States and several Asian countries. What interest? A virus affects us in two stages: first contamination via the mucous membranes and then invasion, that is to say the passage of the virus further inside the body, in the lungs for the coronavirus. However, our mucous membranes have a fully-fledged immune system. “We have memory and immune mechanisms in the mucous membranes that are regulated and expressed independently of immune responses generated by systemic pathways [au global, notamment dans le sang, NDLR]”, explains to HuffPost Cécil Czerkinsky, INSERM research director, mucosal immunologist and vaccine specialist.

With conventional vaccines, the body is forced to develop its defenses (antibodies and T cells) at the global level. Conversely, a vaccine placed in the nose, via a nasal spray for example, will stimulate the mucosal immune system, which prevents the virus from multiplying in our nose. And in this case, it is impossible to be asymptomatic contagious, because the body fights against the virus from the front door. Conventional vaccines have developed a form of mucosal immunity during the first weeks after the injection, but we have clearly seen that this diminished rapidly in the months following the vaccination campaign. And the Omicron variant, which uses different entry gates, didn’t help matters.

Test made in France

Many researchers are working on the issue of mucosal vaccines, but research is still in its infancy. “A dozen companies are relatively advanced. Bharat in particular, an Indian company which is one of the biggest producers of vaccines, is in the process of fairly advanced testing”, specifies Cécil Czerkinsky.

Another possible nasal vaccine is being closely scrutinized by the two immunologists. Because he is French, but not only. In September, the teams of Professor Isabelle Dimier-Poisson (Inrae) announced that they had developed a vaccine capable of 100% blocking transmission in rodents. Promising results, but need to be confirmed in clinical trials on humans.

After setting up a start-up, BioMAP, and developing several public-private partnerships, the team secured funding for a phase 1-2 clinical trial. “Production is being set up and we hope to start clinical trials in June 2023, with results at the end of the year for marketing at the end of 2024”, enthuses with the HuffPost Isabelle Dimier-Poisson.

But why such a long delay? It must first be remembered that the urgency in the face of the pandemic, accompanied by funding and accelerated procedures, is no longer the same. Also, a nasal vaccine is different from an injection vaccine. “The needle makes it possible to pass the barrier of the skin, but for a nasal vaccine, it is necessary to pass the barrier of the mucous membranes, so a suitable formulation is needed”, explains Cécil Czerkinsky. « In addition, the doses needed for manufacturing are ten times greater than for a traditional vaccine. »

A vaccine against variants (and future Covids)

Not to mention that these vaccines are, according to their authors, more advanced and, ultimately, more effective. “A year ago, we raised the possibility that the spike protein [la partie du coronavirus qui s’accroche à nos cellules, NDLR] can mutate and therefore should not be based solely on it”, explains Isabelle Dimier-Poisson. « The proteins we used, which I cannot disclose as a patent is pending, have not mutated since the start of the pandemic. » They are present on Omicron and Delta as on the original Wuhan strain.

The researcher thus hopes that the BioMAP vaccine will be able to block the transmission of any variant of Sars-Cov2. “The end of 2024 may seem far away, but today we know that despite the period of calm, variations can happen, that we will have to continue to do reminders,” she explains. “The one we propose will protect and participate in stopping this pandemic. It will be a vaccine that can be kept for years at 4°C and weeks at room temperature. It will be cheaper than the current vaccines”, promises, full of hope, Isabelle Dimier-Poisson.

Above all, Sars-Cov2 is only the beginning for the researcher. “What we are developing is a platform that we can adapt and which should work for other airborne pathogens, such as influenza, bronchiolitis, tuberculosis”, she lists.

But also against future yet unknown viruses that could cause the pandemics of tomorrow. In other words, prepare for future disasters. That’s good, it’s precisely one of the objectives of the world summit on the Covid.

See also on The HuffPost: on the variants after Omicron, from when to worry?

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