Omicron, the “dizzying” contagion variant: symptoms and vaccines – Corriere.it

Omicron, the “dizzying” contagion variant: symptoms and vaccines – Corriere.it
Omicron, the “dizzying” contagion variant: symptoms and vaccines – Corriere.it

Cases in South Africa grew by 258% in a week, and in 14 days the new variant of the coronavirus became dominant. It is unclear whether Omicron has a greater ability to pierce vaccines

Eyes on the characteristics of the new variant
reported growing in South Africa. At the genetic sequence level it has been identified with the acronym B.1.1.529, but it took its name from the letter of the Greek alphabet Omicron and was added on Friday 26 November by the World Health Organization (WHO) directly to the list of variants of concern (Voc) existing, along with Alpha, Beta, Gamma and Delta.

The first sequenced cases were reported separately starting November 24 from laboratories in Botswana, Hong Kong (where the variant arrived carried by a traveler) e South Africa. The relative growth numbers in the latter country were judged dizzying from the WHO: there were yesterday 2,828 new cases, a 258% increase over the previous week.

It is estimated that about 90% are due to the new variant, which would have supplanted the Delta. However, it is not said that Omicron was born in South Africa: identification also depends on the tracking capacity of the laboratories and the country (together with Botswana and Kenya) is the one that in Africa has the greatest possibility of sequencing the positives.

Because Omicron mutations are unfavorable and worrying

The variant has a genetic profile judged to be unfavorable and defined as worrying. Presents at the same time almost all known mutations from the Alfa, Beta, Gamma and Delta variants, plus other new ones.

Particularly, has 32 mutations in the spike protein (the part of the virus that vaccines use to trigger the immune system against Covid).

If the spike protein changes, even vaccine-elicited antibodies may not recognize it.

Some mutations have never been seen, others have been linked to a variant’s ability to be more transmissible and escape vaccine immunity.

Do the symptoms change?

The South African National Institute for Communicable Diseases (NICD), the public institute of reference on infectious diseases, talks about symptoms similar to previous versions of the virus (including the presence of asymptomatic individuals).

Is there a warning about vaccines?

It is not known whether and to what extent the new variant will be more transmissible or more lethal. All other major variants have been recognized by vaccines, who remained protective of the possibility of being hospitalized or dying, but lost effectiveness (after about six months) of the possibility of being infected.

There is no reason to think it will be different: Extremely unlikely, said Oxford vaccine group director Professor Sir Andrew Pollard, that we will see a re-release of the pandemic as we saw it last year in the vaccinated population.

It still takes at least two to three weeks of monitoring and laboratory testing to glimpse any response. From the genome of the new variant, however, some not very reassuring details are deduced: a partial immune leak is likelybut also that vaccines will still offer high levels of protection against hospitalization and death, South African scientists speculate.

Another cause for alarm comes from the fact that in the lineage B.1.1.529 some parts of the virus are missing that are used by different monoclonal antibodies. In its report on the topic, WHO talks about evidence suggesting an increased risk of reinfection and a growth advantage.

Do the tampons recognize the variant?

The lineage, on the other hand, has a characteristic that offers an advantage for diagnostic systems: The swab analysis searches for three different target genes in the RNA of the virus called S, N and Orf – explains Nicola D’Alterio, general director of the Experimental Zooprophylactic Institute of Abruzzo and Molise (Izsam) -. In the new variant the S gene does not exist. Therefore, there is a high probability that at this time in South Africa a “negative S” buffer is indeed associated with the new variant.

The Delta does not have this particularity. To have the final certainty it is necessary to sequence the genome, because Alpha also has the same characteristic. That’s why the labs are hard at work: identifying other cases, even from swabs already done, could only be a matter of time.

For now, genetic tests have counted 87 cases (77 in South Africa, 6 in Botswana, 2 in Hong Kong, 1 in Belgium and 1 in Israel).

In the Italian database that collects the sequences analyzed so far, Omicron does not appear.

The appeal from many sides is for universal vaccination: variants arise when the virus is left free to circulate.

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