Omicron is not the last worrying species of coronavirus
The new year began with a wave of omicron cases; But will omicron be the last species of the virus, or will a new worrying species emerge in 2022? Experts say they will not be surprised if a new worrying strain of coronavirus appears this year; But it is difficult to predict how fast such a species will spread, how well it will be able to escape the immune system, or whether it could cause more severe illness than previous versions of the virus. Omicron species prevailed over Delta species; Because it is both highly transmissible and can escape the immune defenses of vaccinated and previously infected individuals.
Kartik Chandran, A virologist and professor of microbiology and immunology at Albert Einstein College of Medicine in New York, said the traits allowed the omicron to infect a portion of the population that Delta could not easily infect. Similarly, in order to compete with omicrons of disturbing species of the future, similar gains in transmissibility and safety evasion must be achieved. He said:
There is no reason to believe that there is no genetic space for the virus. I expect more species and similar types of behavior to occur, that is, an increase in the rate of infections following the arrival of a new species.
While the next worrying species may spread easily and deceive the immune system, the trajectory of its other characteristics, such as its pathogenicity, is unclear.
How can the next worrying species be?
Karen Mozman“Given the current rate of coronavirus infection worldwide and the rate at which the virus mutates, it can be predicted that new species will emerge,” a professor of pathology and molecular medicine at McMaster University in Canada told LiveScience. But as we have seen in the last two years of globalization, any new species will not be competitive enough to overcome other species.
Future species can excel in a variety of ways. Theoretically, one of these potential pathways could lead to the development of a virus that is more transmissible and less severe than the omicron. Musman said:
Viruses must multiply and be transmitted to new hosts. The most successful viruses do this by spreading quickly without causing any symptoms; Because the infected host can move easily and transmit the germ to other hosts. It is not helpful for the virus to kill its host before it is released.
Live Science has previously reported that omicron-induced disease may be less severe than previous species. This may be due in part to the fact that this species grows more easily in the upper airways and less in the lungs. The same feature may also help to spread the omicron more easily.
In this regard, the virus appears to have evolved as a result of increased transmission capacity between hosts in a pathogenic pathway that is less pathogenic. However, there is no guarantee that the next worrying species will make the same compromise. Musman said:
The set of mutations that provide the selective advantage may also cause further pathogenicity.
For example, mutations that give a virus the ability to multiply very quickly or to escape the clutches of antibodies that prevent the virus from entering cells can cause the virus to become more severely infected. According to the New York Times, Delta showed such a combination of features; This makes it easier for the coronavirus to spread than all previous strains, and at the same time doubles the risk of hospitalization in unvaccinated individuals compared to alpha strains.
HIV and Ebola are two examples of viral diseases that, although they have been present in humans for decades, have not evolved in the path and their pathogenicity is decreasing. Smallpox was another example of these viruses before they were eradicated.
Chandran said the idea that the pathogenicity of the virus might be reduced over time was not an unreasonable hypothesis; But such a result is not certain. Often, when a virus multiplies and makes mutations, individual mutations within the genome interact with each other and can produce unexpected traits. This phenomenon Epistasis It is called, it makes it very difficult to predict the evolution and behavior of future species.
The great unknowns
In general, there are physical and genetic limitations to the evolution of the SARS-CoV-2 virus. Some of these restrictions prevent the virus from being transmitted indefinitely; Therefore, scientists expect that the virus’s transmissibility will eventually stabilize and increase. At the physical level, Chandran said, viruses must move between the fine line between stability and instability, and this balancing act limits their transmissibility.
In fact, the virus is a microscopic box of genetic material, and the box must be strong enough to hold the genetic material inside the host body and in the outside world. However, in order to infect the cells, the box must be opened and the genetic material of the virus removed. If the box is too stable, the virus will not be able to open it and infect the cells efficiently. Even if it is very unstable, the virus can not remain active for a long time after it is removed from the infected person through sneezing.
At the genetic level, a virus can accumulate many mutations in its genome before it can malfunction. For example, a virus needs its own spike protein to attach itself tightly to a receptor on human cells to trigger an infection. Spike mutations can help microbes escape antibodies produced against past species.
The omicron has about 30 mutations in its spike, some of which help it escape the immune system; But there is probably a limit to the number of mutations that can accumulate in the spike before its ability to attach to human cells begins to decline.
In this sense, the corona virus probably still has room to move genetically. According to a study published in the December 2 issue of the journal Science, the SARS-CoV-2 virus is likely to tolerate a large number of escape mutations (mutations that help the virus escape antibodies); While still maintaining the ability to attach to human cells. Dr. Jonathan AbrahamSenior author of the study and assistant professor of microbiology at Harvard Medical School said:
The high structural flexibility we observed in the SARS-CoV-2 spike protein suggests that omicrons are probably not the end of the virus’s story.
Other unknowns make it difficult to predict the future evolution of the SARS-CoV-2 virus. One of the important questions is where the next worrying species comes from; Because it may not be descended from Omicron.
Omicron, in contrast to the Delta, originated from a different branch of the corona virus family tree; Even though the delta was predominant at the time. The next disturbing species may have a similar origin to the story.
At the same time, the animal hosts of the Corona virus should not be ignored. The SARS-CoV-2 virus can infect a variety of animals, including mink, domestic mink, cat, white-tailed deer, and primates. This has raised concerns that the virus, while circulating in animals, could produce mutations that could be more infectious or deadly to humans, or mutations that could reduce the effectiveness of vaccines. Chandran pointed out:
For this to happen, the corona virus must jump back into the human after infecting the animal, and in some cases, the virus may mutate so much that it can no longer infect humans. The genetic pathway of the virus can be very different in other hosts.
Animal-to-human transmission was reported in Mink farms early in the world, and it is possible that other species could bring the virus back to humans. For this reason, scientists must continue to detect the SARS-CoV-2 virus in humans as well as animals; Because animal reservoirs of the virus can be problematic in the future.
Reduce the risk of disturbing species
What can we do to reduce the risk of disturbing species? Chandran said:
What we need to do is reduce the space that the virus has to multiply, and the way we can do that is through vaccination.
As of Jan. 10, about 67.4 billion people worldwide had received at least one dose of the Covid 19 vaccine, according to the New York Times. Thus, approximately 40% of the world’s population is not fully vaccinated. Even if vaccines provide partial protection against future species, as they do for omicrons, the chances of catching the virus and passing it on to others will be reduced.
However, vaccination in combination with other measures such as wearing a mask and social distancing and repeated testing can work best. More importantly, increasing the number of people vaccinated by preventing severe illness will reduce the pressure on the health care system.
Preliminary evidence released Jan. 3 in the medRxiv pre-published article database shows that even if the omicron species can escape some of the vaccine-derived antibodies, other immunizations against the vaccine will still inhibit severe infections. Experts have not yet reviewed this study; But it does show that vaccines produce sustained responses from donor T cells that, upon detection of SARS-CoV-2, boost the immune response and kill dead T cells.
These T cells show cross-reactivity against Delta and Omicron species; That is, they can detect and target both versions of the virus. Likewise, T cells can protect against disturbing species that may appear in the future.
In general, the more people are infected or vaccinated, especially several times, the more immunity will be developed, which will potentially be effective against different species. As the level of this immunity increases in the population and around the world, the overall evolution of SARS-CoV-2 is likely to slow down and globalization will become endemic. This is how the world ends; But until then, we will probably still encounter some worrying new species.