It is written in the genes, the new identikit of the Omicron variant of the SarsCoV2 virus. New data explain its great ability to transmit, which everywhere is causing the curve of the Covid-19 epidemic to rise and at the same time indicate that it is unable to cause a serious disease. Another element is that its mutations are not only present in the Spike (S) protein with which the virus captures human cells, but in its molecular heart, that is, in the nucleocapsid which contains the genetic material of the virus. For all these characteristics, "the Omicron variant could be a completely new virus compared to the other versions of SarsCoV2 that we have known so far", observes virologist Francesco Broccolo, of the University of Milan Bicocca.
"Of the many studies on the Omicron variant published so far, the two most solid he observes - show that mutations on protein S promote transmissibility thanks to the stronger binding of the protein to the cell's Ace receptor, but that in fact this greater ability to transmit is balanced by a reduced infection ". The expert refers to the research, both pending review by the scientific community, conducted by the Japanese consortium Genotype to Phenotype (G2P-Japan) and the University of Cambridge.
"Both studies indicate that greater transmissibility does not necessarily mean greater infection: in the case of Omicron this means that between its Spike protein and the cells' Ace receptor there is a strong attraction like that of a magnet, but then - he continues - the cell receptor that should favor the fusion process has a poor efficiency ". In essence, he continues, "the virus tries to enter the cell as if it were opening a door: it inserts the key, turns it and pushes the door. With the Omicron variant we are faced with a virus that is very good at inserting the key, but manages to turn it only a few times ". In other cases, such as for the Delta, the opening of the first time automatically opens that of the neighboring cells, as in a domino,and the virus invades them one after the other with the famous video game PacMan, "but Omicron is not PacMan," says Broccolo. That is to say that "unlike the Delta, Omicron is not syncytogenic, meaning a cell does not merge with adjacent healthy ones," observes the virologist. The British Minister of Health, Sajid Javid, also spoke of a lower virulence, for whom after the third dose of the vaccine the risks of hospitalization are 90% lower than the Delta variant.Sajid Javid, for whom the risks of hospitalization after the third dose of vaccine are 90% lower than the Delta variant.Sajid Javid, for whom the risks of hospitalization after the third dose of vaccine are 90% lower than the Delta variant.
For Broccolo it is very likely that "Omicron is finding its ecological niche and that it is progressively replacing the Delta, but in Italy we still have about 60% of Covid cases from Delta and about 40% from Omicron". It is in these percentages, combined with those on vaccination coverage, that the causes of the increase in hospitalizations should be sought. "Being vaccinated for over four months means you are at greater risk of infection, both with Omicron and with Delta and it cannot be excluded that the growth in the hospitalization curve is due to a greater number of Delta cases".
Finally, the fact that "in its nucleocapsid there are six mutations in its nucleocapsid, against the three in the Delta, and this - Broccolo observes - could further jeopardize the efficiency of antigenic tests".
It can still be hypothesized that "it may be the first step towards the end of the pandemic, but Omicron is so transmissible that currently it cannot be excluded that it may generate a new variant".
