The sub-variants of Omicron BA4 / 5 are scary as they have less ‘good’ characteristics than the previous ones but, fortunately, our immune system has what it takes to fight them.
The Omicron sub-variants of Sars-CoV2 circulated undisturbed throughout the summer without allowing us the summer break which, for example, grants us the flu. In a previous article we analyzed the impact of these extremely contagious but less pathogenic sub-variants: contrary to what one might expect, such contagious variants cause a very high number of deaths despite the lower aggressiveness.
Covid, why so many deaths compared to the summer of 2020?
by Aureliano Stingi
All the sub-variants of Omicron are characterized by a very high contagiousness and immunoevasiveness: in practice, they have the ability to re-infect vaccinated or recently recovered subjects. Immunoevasiveness is a characteristic that the virus can acquire thanks to some random mutations that modify it in order to make it less ‘visible’ to our immune system. Many subjects recovered from the previous infections or vaccinated have in fact contracted the Omicron variants in recent months.
The BA4 / 5 sub-variants took off in Europe a few weeks after the transition of the Omicron BA1 / 2 sub-variants and are currently prevalent practically everywhere in Europe. Virological data concerning the BA4 / 5 sub-variants have recently been published: these data have been obtained in the laboratory through experiments that are usually carried out on in vivo models, ie on experimental animals.
The data confirm that the BA4 / 5 sub-variants possess a higher intrinsic contagiousness, are capable of immunoevasion and, finally, are probably more pathogenic. Let’s analyze all these features:
- greater contagiousness: this feature should not surprise us, the BA4 / 5 sub-variants have literally supplanted the previous BA1 / 2 sub-variants in a short time, becoming dominant. The variants that have followed one another since the beginning of the circulation of Sars-CoV2 in humans have been gradually more contagious.
- immunoevasive capacity: as mentioned, it is the ability of the virus to bypass the previously stimulated immune defenses. In vitro the BA4 / 5 sub-variants are able to bypass the antibodies stimulated by the BA1 / 2 sub-variants but fortunately our immune defenses are not only formed by neutralizing antibodies. In fact, a subject who has just recovered from a BA1 / 2 infection could potentially become infected with the BA4 / 5 sub-variants but probably would not suffer a symptomatic disease as the previously produced T lymphocytes would protect him.
- Potential increased pathogenicity: the pathogenicity of a virus is the ability to create damage in the host organism. It is hypothesized that the BA4 / 5 sub-variants are more pathogenic than BA1 / 2 since their fusogenic capacity has been observed in vitro: in practice, Sars-CoV2 induces the fusion of host cells in which it reproduces. The formation of syncytia (the fusion of 2 or more adjacent cells) is deleterious and damages the affected tissues. A variant with a high fusogenic potential can cause very serious damage in infected tissues such as, for example, the bronchi and lungs.
So, in summary, the sub-variants of Omicron BA4 / 5 are more contagious, are able to evade the immune defenses and are more pathogenic. Despite these characteristics which tend to be worse, the BA4 / 5 wave can be considered comparable to the BA1 / 2 wave: why?
Sars-CoV2 circulates in an environment that is not unprepared from the immune point of view since practically the entire population (at least Western) has come into contact with the virus at least once: directly through an infection or indirectly with the vaccine.
The virological characteristics observed in the laboratory in in vivo models serve us to better understand the variants but, fortunately, they do not necessarily present themselves in the population that, in fact, has built the immunity wall.
The data on hospitalizations in South Africa confirm that the BA4 / 5 wave was decidedly less violent than the previous BA1 / 2 and this mainly thanks to the healing immunity and the administration of the vaccine in the population.
So what does the BA4 / 5 variant teach us? Mainly two things:
- there is no biological rule that makes a virus evolve to become ‘better’. The BA4 / 5 sub-variants show us that their pathogenicity is greater than the previous BA1 / 2.
- the effects of a virus in an immunologically unprepared population are completely different than in an immunologically competent population. Vaccination campaigns and healings help build a solid immune wall.
Today we do not have the tools to know what the next variant of Sars-CoV2 will be like, but we can use the same rules and recommendations that we have used until now: let’s get vaccinated and avoid contracting the infection in all ways.
REF:
https://www.salute.eu/2022/09/05/news/covid_morti_estate_paradosso-363884411/
https://www.medrxiv.org/content/10.1101/2022.08.24.22279197v1.full.pdf
https://www.cell.com/cell/fulltext/S0092-8674(22)01190-4
https://www.epicentro.iss.it/coronavirus/pdf/sars-cov-2-monitoraggio-varianti-rapporti-periodici-28-luglio-2022.pdf
https://erictopol.substack.com/p/the-pandemic-and-the-boiling-frog?utm_source=profile&utm_medium=reader2
Aureliano Stingi, doctor in molecular biology works in the field of precision oncology. He collaborates with the World Health Organization in the battle against Covid19-themed fake news
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