In order to fight the pandemic in the long term, it is crucial to understand why one variant prevails over another.
In a new study from the University of Bern, researchers found important answers by comparing the spread and transmission of different emerging variants in parallel.
This approach is now applicable to the comparison of new variants, such as Delta and Omicron.
As new SARS-CoV-2 variants continue to emerge and drive the pandemic, researchers have studied emerging variants in animal (in vivo) and biophysical interaction and cell culture (in vitro) models.
The originality of this new study is to have put the variants in direct competition in multiple models to reveal why some variants had a real advantage to spread globally.
The team says taken independently, each of the variants appears to be as effective as their progenitor, the initial virus: it is difficult to separate them.
By recreating the natural conditions of competition, where an emerging variant and its progenitor are simultaneously present, it becomes possible to truly detect which variant will preferentially propagate and be transmitted to another individual.
The challenge of the study was to associate different experimental models to better understand these mechanisms, and the combined analyses enabled us to discriminate the differences between the variants.
The competition between the alpha and beta variants and their progenitor clearly shows that the alpha variant has an advantage.
The team found that the alpha variant dominates and spreads better in the upper respiratory tract and transmits more efficiently. All the models also showed that the beta variant is the ‘big loser.’
It seems that the beta variant has benefited from favorable epidemiological circumstances to develop locally.
On the other hand, the alpha variant, which has spread globally, has demonstrated its intrinsic high transmission potential through its spike mutations.
Predicting which variant will better spread and why continues to be a challenge. Only in-depth studies can provide a better understanding of the factors associated with this spread.
Now that a significant proportion of the population is vaccinated, scientists will also have to consider the impact of immunity on the advantage of new emerging mutants.
If you care about omicron, please read studies about drug that could help treat lung damage in COVID-19, and Pfizer vaccination that provides 70% protection from Omicron.
The study is published in Nature. One author of the study is Charaf Benarafa.
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