With its new variants, covid is always at the forefront of scientific efforts to end the pandemic, something that scientists will try to reverse with two new weapons.
Only ten vaccines today make up the select club of formulas approved for emergency use against covid-19 by the World Health Organization (WHO), to which are added 20 immunizers authorized locally in several countries.
However, the number of vaccine candidates in clinical development is much higher: 170 in 69 nations, plus 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 hitherto unknown virus, Sars-CoV-2.
Immunizers have significantly reduced the number of hospitalizations, an important achievement, but insufficient to get closer to the goal of ending the pandemic once and for all.
Today, laboratories have a better understanding of the virus and its mutations, such as the delta and omicron variants, the latter with a much more distant composition from the original in 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?
Scientists are investigating this possibility.
Check out below two promising advances, according to the WHO and experts, in the laboratories where the next vaccines against covid-19 are prepared.
1. The intranasal route, an impenetrable barrier for the virus?
The scientific community’s most ambitious goal is to achieve sterilizing immunity, that is, not only protecting people against serious illness or death, but also preventing them from becoming infected.
And one of the ways to achieve this may be to administer the vaccine through the nose.
“Now there are many infected, but thanks to vaccines, few end up in the hospital. What then is needed to prevent infections? Having a vaccine that prevents infection and that can be administered intranasally”, says Amílcar Pérez Riverol, researcher at the Support for Research in the State of São Paulo (FAPESP), BBC News Mundo, the BBC’s Spanish-language news service.
While intramuscular vaccines trigger a generalized immune system response, intranasal vaccines act locally in the nose, lungs and stomach. As a result, they impose a barrier to the virus that is difficult to overcome.
The specialist indicates that, when inserted into the nostrils, they induce a protective response in the virus entry pathway, activating the secretion of immunoglobulin A (IgA) antibodies.
In an article published in the scientific journal Science last August, researchers Frances E. Lund and Troy D. Randall, from the University of Alabama (USA) specify that intranasal immunizers “provide two layers of additional protection: the vaccine IgA and the memory B and T cells that live in the respiratory mucosa”.
These memory cells remain in the body long after the infection is gone, but they do not forget the viruses or bacteria they fought off, and if they encounter these pathogens again, they recognize and attack them.
The researchers explain that even if a virus variant crosses the first barrier and an infection occurs, memory B and T cells respond more quickly to familiarization with the antigen, which “stops viral replication and reduces spread and transmission.” .
Another advantage offered by nasal vaccines is time, as intramuscular vaccines need two to three weeks to “upgrade” the immune system to its highest degree of protection.
Currently, there are eight WHO-recognized intranasal covid-19 vaccine projects.
The most advanced in this field is that of the Indian biotechnology multinational Bharat Biotech, whose immunizer is already in phase 2/3 of human trials, unlike the other projects, which are in the initial stages.
Among them, the one led by scientists Akiko Iwasaki and Benjamin Goldman-Israelow, from Yale University (USA), stands out, who managed to successfully immunize mice against respiratory viruses such as the coronavirus.
“Results in preclinical models are promising. We believe it will work with variants that are currently circulating as well as future variants,” Goldman-Israelow tells BBC New Mundo.
But not everything is roses.
Experts warn that 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 influenza, proving the difficulty of developing this type of drug.
A complicated challenge that is also taken on by the team led by virologist Luis Enjuanes, from the Centro Superior de Pesquisa Científica de España (CSIC).
Enjuanes explains to BBC News Mundo that his immunizer shows an important qualitative advantage “in contrast to other mRNA-based vaccines, which do not multiply and self-amplify”.
“Our RNA carries the information to replicate itself, increasing the number of molecules we inject and multiplying each one, amplifying it more than a thousand times, which makes the immune response stronger and longer lasting”, he says.
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 not known, for now, when the first of them will begin to be administered to the population. Laboratories avoid announcing approximate dates.
“I don’t see any approval before the second half of 2022,” says Pérez Riverol.
2. A ‘super vaccine’ that attacks all coronaviruses
Pfizer has begun clinical studies for a new omicron-adapted vaccine.
But if we’ve learned anything from the pandemic, it’s that no matter how quickly we create and distribute a vaccine against Covid-19, there may be a new, faster variant that catches us off guard and limits the effects of injections.
Also, Sars-CoV-2 is the most famous but not the only coronavirus. In recent decades, other dangerous variants have caused significant outbreaks, such as those that cause SARS (Severe Acute Respiratory Syndrome) and Mers (Middle East Respiratory Syndrome).
That could end up with a definitive formula that attacks all variants: the one known as the pan-coronavirus vaccine.
“Let’s not run after the next variant.” The White House’s main medical adviser, Anthony Fauci, took a position on January 12 in favor of a future vaccine that will allow us to prevent and fight not only the covid-19 virus 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 against all coronaviruses, has become even more apparent,” Fauci told a committee at the US Senate.
Making these vaccines, explains Pérez-Riverol, is a very complex process, and one of the ways being investigated is to attach the S proteins of the virus to nanoparticles.
The S proteins are essential for the virus to bind to the human cell, so part of the current vaccines consists of implanting harmless modifications in these proteins on the surface of the 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, the recipient will be immunized against a wide diversity of variants of the coronavirus. Therefore, the immune system will be better prepared to respond not only to existing variants, but to future ones”, he explains.
In this area, the project of the Walter Reed Army Research Institute (WRAIR) in the US stands out, which is working on a vaccine called SpFN based on ferritin nanoparticles, a protein that stores and transports iron and which, when attached to human cells, can prevent the virus from replicating.
This immunizer passed phase 1 of human trials in December 2021 with positive results against several variants, including omicron, and its efficacy and safety will be tested in phases 2 and 3 in the coming months, announced Kayvon Modjarrad, director of infectious diseases at WRAIR
SpFN uses a 24-sided soccer ball-shaped protein, which allows scientists to bind the spikes of various coronavirus strains on different faces of the protein, Modjarrad added in an interview with US news site Defense One.
The Pan-Corona initiative, the result of a collaboration between China and Cuba, also stands out in this line.
Based in 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 an antibody response in the human body by combining fragments of already known viruses.
Scientists working on these projects haven’t dared to announce estimated dates either, so it’s unknown when the first “super vaccines” that protect us against current and future variants might be available.
The WHO, in any case, hopes that the two mentioned advances will be followed by new and important advances in the field of new vaccines against covid.
“Just because there are more vaccines on the market doesn’t mean we should stop making progress in research and development. We have to keep looking for better options,” WHO chief scientist Soumya Swaminathan told Reuters in a recent interview.