It is quite likely that the coronavirus was already circulating among humans in 2019, but words like Sars-Cov-2 and Covid-19 were not part of the current vocabulary. Two years later, the emergence of variants such as Ômicron, identified in Africa, casts doubt on the future.
When, finally, can we talk about an end to the pandemic? Will Sars-Cov2 continue to evolve indefinitely? Will new, more lethal variants emerge? More transferable?
If two years are nothing in terms of human history—and for scientific development—the ability of this virus to spread is the only explanation for the new world being built on the rubble of this generation’s greatest epidemic.
With all the care taken from science itself — which has no problem revisiting concepts, updating them, confronting them and, whenever necessary, correcting them — we should not wait for the complete eradication of the coronavirus.
Most likely, the virus will become more and more communicable and less and less lethal. And humanity learn to live with it, in this new normal.
At least this is what the scientific knowledge accumulated in this very short period of time indicates, in which a previously unknown virus started to infect people, spread around the world, killed more than 5 million human beings, precipitated an unprecedented race for the development of vaccines , broke economies, unmasked deniers and exposed social, financial and educational inequalities.
Although the virus is not exactly a living being, its evolution mechanism is very similar. These processes are a consequence of better adaptive randomness—successful accidents.
As the infectious disease physician and sociologist Ricardo Palacios, former medical director of clinical research at the Butantan Institute explains, “there is no such thing as an intelligent virus”, so this “is not a planned process”. “It happens by chance.”
Coronavirus mutations
“Viruses replicate by infecting cells and generating a mechanism to create copies in these cells. These mechanisms are not perfect and many errors happen in the process, causing mutations. In most cases, these mutated viruses are not viable. But, eventually, there are mutations that confer an advantage over the original virus”, contextualizes Palacios.
An example: if a mutation makes the version more transmissible, it ends up replicating faster and faster.
“Viruses evolve in response to host pressures that block or limit their multiplication”, explains pharmacist Oscar Bruna-Romero, professor at the Department of Microbiology, Immunology and Parasitology at the Federal University of Santa Catarina.
“There are several possibilities of pressure, the most important being cellular, when the virus changes to infect other cells or hosts, for example from an animal to man, and the immunological pressures, which lead to trying to escape our immune system by changing the parts of the virus that are seen by our antibodies and lymphocytes.”
According to the professor, if evolution is something normal in all beings, in viruses it is a very accelerated process, due to “its genetic simplicity and extremely high capacity for multiplication”. Few viruses can quickly generate billions of copies in an infected human.
That’s why containment measures—social distancing, masks, sanitization—are important.
“If the virus has a lot of opportunity to infect many hosts and replicate, it will be making more and more bets. [com o acaso]. Eventually, something he does can do him some good. And that’s what we want to avoid”, points out biomedical scientist Mellanie Fontes-Dutra, coordinator of the Covid-19 Analysis Network.
Since mutations are a matter of chance, it is a matter of proportionality. Obviously the more the virus spreads, the more mutations occur.
In the case of Covid-19, scientists have so far identified five strains that have been especially successful in this evolution. They were named with the Greek letters Alpha, Beta, Gamma, Delta and Ômicron. Among researchers, they are called VOC, the acronym in English for “concern variants”.
Despite having their own characteristics, they also have mutations. So scientists have been monitoring subvariants — small genomic changes within a lineage — fearful of the emergence of new VOCs.
“[As análises] show that these variants are evolving, creating new evolutionary branches, and this has implications both for the need for genomic surveillance to monitor them, and for the need to implement more effective measures to control this transmission”, explains Fontes-Dutra.
“A subvariant, or underscore, is generally a ‘descendant’ of a known lineage,” he adds.
In the case of the newly discovered Ômicron variant, one of the main questions is whether it will outperform other strains.
“Any variant that comes to compete with Delta must have mutations that bring characteristics of greater transmission than Delta. This is the great concern with the new variant detected in samples from Botswana and which was able to replace the Delta variant in Gauteng Province, South Africa”
Ricardo Palacios, former medical director of clinical research at Instituto Butantan
Assumptions about the fate of the coronavirus
In nature, there is no secret: whoever adapts best survives. In the case of a virus, this means that the variants that manage to infect more people in less time end up being more successful. They end up overlapping the rest and that’s why Delta was considered the dominant one across the planet.
On the other hand, a high lethality would not be a good deal: in the transmission chain, in cold terms, a dead host is not useful for the virus to survive.
The good news is that there are limits to this evolution. “They will at some point reach their maximum improvement, limited by our own biological limitation as hosts”, says Oscar Bruna-Romero, who believes that in the coming years Sars-Cov2 should “decrease dangerousness and maintain or increase transmissibility” .
“Microorganisms considered to be very successful, such as the cytomegalovirus or the protozoan Toxoplasma gondii, are those that transmit a lot, they are in more than half of some human populations, without making much noise — most do not even know they are infected”, he points out.
Ômicron analysis will help test the hypothesis that the coronavirus would be close to its evolutionary limit. “Many of the mutations found in it were already present in other variants. This convergence can reach a threshold of stabilization of the virus’ genetics. In other words, it reached a level of mutations close to the maximum possible in order to have advantages and giving little scope for evolution”, analyzes Palacios.
“But we don’t know how much longer this stabilization will take. We have little time to interact with the virus and the lack of control in some regions, as well as infections in other animal species, can bring new mutations that are unknown until now. We need to keep following this evolution”, ponders the infectious disease specialist.
“The recent discovery of Ômicron alerts the world to the possibility that we have even more variants emerging, but possibly at a slower pace than in the last year.”
In an article recently published by Nature (https://www.nature.com/articles/s41591-021-01421-7), the Italian virologist Roberto Burioni, a professor at the Vita-Salute San Raffaele University, in Milan, spoke about the which hopes to be a final variant of the coronavirus.
This hypothetical apex would necessarily be that of a virus with maximum transmissibility that, when converted into a dominant strain, would not allow great future variations.
According to the Italian, three scenarios are possible in this regard. The first is the best for humanity: with the majority of the world’s population immunized, the coronavirus would not be able to evolve in order to “dribble” vaccines.
Would be a game over at the same level already seen by other known viruses such as measles, mumps, polio, and smallpox—the disease may even resist and eventually have a localized outbreak; but the vaccinated could breathe easily, and without masks.
Burioni’s second hypothesis is that the coronavirus can break through the vaccine blockade, at a price: being less lethal and thus hiding from our immune system boosted by immunizers.
He notes that the Beta and Gamma variants are indications of this. Current vaccines are less protective against them, but those who become infected with such strains usually do not develop severe cases.
Possibility of dribbling the vaccine
But not everything is optimism. The Italian also presents a worrying scenario: mutations continue to occur and some variant manages to fool the vaccines while maintaining — or even aggravating — their transmissibility. And, who knows, even the lethality.
This would require that new versions of the immunizers be developed in order to also protect against this possible new strain.
This improvement in vaccines is not unprecedented in medicine. The annual influenza immunization campaign usually considers the most recent variants of the virus in circulation.
If Sars-Cov2 becomes seasonal, health systems will have to contemplate periodic and up-to-date population immunization.
While vaccination is the best tactic to defeat the coronavirus, there is constant concern that, by containing the already known variants, some mutation that eventually bypasses the vaccine will eventually spread more easily — precisely because the others are blocked by immunity collective.
“This is one of the biggest concerns of all vaccine developers”, comments Palacios. “Fortunately, the phenomenon has not been described with any vaccine so far. All existing ones today have a sufficient response to protect against serious illness caused by all variants [conhecidas], and none generated pressure to select a new variant.”
Oscar Bruna-Romero adds that, “if big changes happen, generating new variants, they could manage to evade vaccines [existentes hoje] and become preponderant”.
That’s why it’s important to run out of time and quickly immunize as many people as possible. The more unvaccinated people circulating, the greater the chance that the virus could be transmitted at full speed—and the more mutations taking place.
Again, a mathematical question: the high probability of chance setting up and emerging a mega-master-blaster-plus version coronavirus.
“The most important thing is to stop the virus as quickly as possible, leaving the least number of individuals susceptible to infection”, defends the pharmacist.
Reference: CNN Brasil
