Only ten vaccines today make up the select club of formulas approved for emergency use against covid-12 by the World Health Organization (WHO), to which are added twenty formulas locally authorized in several countries.
However, the number of vaccine candidates in clinical development is much higher: 170 in 69 nations, in addition to 194 in preclinical development, according to WHO data.
Two years have passed since the global impact of the pandemic forced the design of new vaccines against a then unknown virus, SARS-CoV- 2.
These have decimated the severity of the disease and reduced infections, an important achievement but insufficient to approach the goal of ending the pandemic once and for all.
Laboratories today have a better understanding of the virus and its mutations, such as the delta and omicron variants, the latter with a genetic composition much further from the original of Wuhan.
So, are we in a position to create the definitive formula that ends the virus once and for all or normalizes living with it?
The scientists are trying and these are two promising advances, according to the WHO and the experts, in the laboratories where the next vaccines against covid are prepared-19:
one. The intranasal route, an impenetrable barrier for the virus?
The most ambitious objective of the scientific community is to achieve sterilizing immunity, that is, not only protect people against serious illness or death, but also prevent them from becoming infected.
And one of the ways to achieve this may be administer the vaccine through the nose.
“Now there are many infected but thanks to few vaccines end up in the hospital. What is missing then to stop the infections? Having a vaccine that prevents infection and that could be provided by those administered intranasally, ”molecular biologist Amílcar Pérez Riverol, a researcher at the São Paulo State Research Support Foundation (FAPESP), explains to BBC Mundo.
While intramuscular vaccines trigger a generalized response from the immune system, intranasal vaccines act locally in the nose, lungs and stomach. With this, they impose a barrier on the virus that is difficult to overcome.
The expert indicates that, when nebulized in the nostrils, they induce a protective response in the route of entry of the virus, activating the secretion of immunoglobin A (IgA) antibodies.
In the article “Aroma of a vaccine”, published in the journal Science last August, researchers Frances E. Lund and Troy D. Randall, from the University of Alabama (USA) specify that intranasal formulas “provide two additional layers of protection: the IgA from the vaccine and memory B and T cells residing in the respiratory mucosa”.
These memory cells remain in the body for a long time after the infection has disappeared, but they do not forget the viruses or bacteria that they fought and, if they return, they recognize and attack them.
These researchers explain that, even if a variant of the virus overcomes the first barrier and infection occurs , memory B and T cells respond more quickly to being familiar with the antigen, which “prevents viral replication and reduces propagation and transmission.”
Another advantage offered by nebulized vaccines is time, since intramuscular vaccines need between two and three weeks to “update” the immune system to its highest degree of protection.
Currently there are eight intranasal vaccine projects against covid- recognized by the WHO.
The most advanced in this area is that of the Indian multinational biotech company Bharat Biotech, whose product is already in phase 2/3 of human trials , unlike the other projects that are in earlier stages.
Among these, the one led by scientists Akiko Iwasaki and Benjamin Goldman-Israelow, d and Yale University (USA), who managed to successfully immunize mice against respiratory viruses such as coronavirus.
“The results in preclinical models are promising. We believe that it will work with the variants that are currently circulating, as well as with future variants,” Dr. Goldman-Israelow told BBC Mundo.
But not everything is rosy. Experts warn that the favorable results in mice do not guarantee the same response in humans. In addition, today only two vaccines administered through the nose are marketed globally, FluMist/Fluenz and Nasovac, both for the flu, proof of the difficulty of developing this type of medication.
A complicated challenge that is also taken on by the team led by the virologist Luis Enjuanes, from the Spanish Higher Center for Scientific Research (CSIC).
- “Gripalizar” the covid: what is the strategy proposed by Spain and what the experts say
Enjuanes explained to BBC Mundo that his formula shows an important qualitative advantage “in contrast to other mRNA-based vaccines, which do not multiply and auto-amplify”.
“Our RNA carries the information to replicate, increasing the number of molecules that we have injected and multiplying each one amplifying it more than a thousand times, which makes the immune response stronger and longer-lasting”, he indicated.
Laboratories in Russia (with a variant of Sputnik V), Hong Kong, the United Kingdom (AstraZeneca) or Cuba are also working on intranasal vaccines.
It is unknown, for the moment, when the first of them will begin to be administered to the population. The laboratories avoid announcing approximate dates.
“I do not see any being approved before the second semester of 2021”, says Dr. Pérez Riverol.
two. A “supervaccine” that attacks all coronaviruses
Pfizer has started clinical studies for a new vaccine adapted to omicron.
But, if we have learned something in the pandemic, it is that no matter how fast we are in creating and distributing a vaccine against covid-: there may be a new faster variant that catches us off guard and limits the effects of the injections.
Also, SARS-CoV-2 is the most famous but not the only coronavirus. In the past decades, other dangerous variants have caused significant outbreaks, such as those causing SARS and MERS.
This could end with a definitive formula that attacks all variants: the one known as the pan-coronavirus vaccine.
“We are not going to pursue the next variant”. The chief medical adviser to the White House, Anthony Fauci, took this position on 12 of January in favor of a future vaccine that allows us to prevent and combat not only the covid virus-19 but also other similar ones that may arise in the coming years.
“The importance of developing a pan-coronavirus vaccine, that is, one that is effective against all variants of SARS-CoV-2 and ultimately instance against all coronaviruses, it has become even more apparent,” Fauci told a US Senate committee.
Manufacture these vaccines, explains Dr. Pérez-Riverol, is very complex, and one of the most two that are investigated consists of adhering the S proteins of the virus to nanoparticles.
The S proteins are key for the virus to bind to the human cell, so part of the current vaccines consist of deploy harmless modifications of these on the surface of cells to induce the immune response.
“If you use a nanoparticle and combine it with S proteins from different variants of SARS-Cov-2 with wide antigenic diversity , those who receive it will be immunized against a wide variety of variants of the coronavirus. Therefore, the immune system will be more prepared to respond to those that can be generated and have been generated”, he explains.
In this area, the project of the Walter Reed Army Research Institute (WRAIR) in the USA stands out, which is working on a vaccine candidate called SpFN based on ferritin nanoparticles, a protein that stores and transports iron and that, attached to to human cells, it can prevent virus replication
This compound passed phase 1 human trials in December 2021 with positive results against various variants, including omicron, and in the coming months its efficacy and safety will be tested in phases 2 and 3, announced Dr. Kayvon Modjarrad, director of infectious diseases at WRAIR.
SpFN uses a soccer ball-shaped protein of 19 faces, which allows to the scientists join the spikes of various strains of coronavirus on different faces of the protein, Modjarrad said in an interview with the US specialized portal Defense One.
The Pan-Corona initiative also stands out in this line, the result of a collaboration between China and Cuba.
Based on the city of Yongzhou (in the central Chinese province of Hunan) and led by Cuban scientists, the project seeks to create a vaccine that induces the antibody response in the human body from the combination of already known virus fragments.
The scientists working on these projects have not dared to announce estimated dates either, so it is unknown when they could be available the first “super vaccines” that protect us against current and future variants.
The WHO, in any case, He hopes that the two advances mentioned will be followed by new and important advances in the field of new vaccines against covid.
“The fact that there are more vaccines on the market does not mean that we should stop making progress in research and development. We have to keep looking for better options,” WHO chief scientist Soumya Swaminathan said in a recent interview with Reuters.
Remember that can receive notifications from BBC World. Download the new version of our app and activate it so you don’t miss our best content.
- Do you already know our YouTube channel? Subscribe!