More than a month of omicron: What is known and what is expected of the evolution of this variant of the coronavirus?

Omicron It is highly transmissible and it is because it has accumulated a very high number, greater than other times, of mutations and a combination of these not seen until now. What is expected of the evolution of this variant? Does SARS-CoV-2 behave like other coronavirus? Is the pandemic going to become endemic?

First identified as B.1.1.529, this variant presents an amalgam of more than 30 mutations in the spike protein, the one that the virus uses to enter the human cell and the common target, with different technologies, of current vaccines, which today do not have the changes present in omicron and other variants.

While some of the mutations of omicron They had already been observed in beta or alpha, it is the first time that the scientific community has seen them together. Since the end of November it was declared as worrying.

ORIGIN YET UNKNOWN

It was first detected in South Africa Y its origin is still unknown; there are two main hypotheses.

One, that its evolution occurred in a very immunosuppressed person infected with covid-19 for an extended period of time, perhaps more than 300 days. By not being able to eliminate the coronavirus, it multiplied and mutated continuously, which could have led to this variant.

The other possibility is what is called reverse zoonosis, according to which SARS-CoV-2, over time, would have passed from humans to animals. The virus would evolve differently in the animal host and by doing so could re-enter the human population, but this time as a different virus.

Whatever its origin,

MORE CONTAGIOUS BUT HOW MUCH AND WHY?

It is more contagious, more than the delta, which has already surpassed the other lineages, but it is difficult to establish how much more and still premature to explain why, admits Salvador Iborra Martín, an expert in immunology and infections at the Complutense University of Madrid. And it is that the populations to be compared are not the same; now, for example, the percentage of people who have passed the infection is higher than a few months ago, also the number of vaccinated, so the behavior of the virus and of society is not the same (there is more relaxation).

However, there are preliminary studies – not subject to review by other researchers and therefore not published in scientific journals – that advance this knowledge;

Scientists at the University of Hong Kong concluded in ‘in vitro’ experiments that the variant prefers to multiply cells in the bronchi rather than those in the lungs.

It is in the former where it would multiply about 70 times faster than delta and the original SARS-CoV-2, thus accumulating more amount of transmissible virus in less time. In the lungs, however, it would replicate less efficiently – about 10 times less – than the Wuhan coronavirus, suggesting less severity of the disease. covid-19.

Japanese researchers also conducted a study in this regard, also preliminary and this time in hamsters; found that omicron is less pathogenic because it favors less fusion between infected cells. One of the ways in which the virus is transmitted is by helping infected cells to contact their neighbors and it seems that omicron This he does not know how to do so well.

They also analyzed the spread of omicron and other variants: the first is between 3.05 and 5.57 times more transmissible than delta (according to data from South Africa or the United Kingdom, respectively).

DOES WHAT ABOUT SARS-COV-2 DO OTHER CORONAVIRUSES?

Viruses always mutate, within their biological process, and replicate. Although there are correction mechanisms in this copy system, these sometimes fail causing an accumulation of errors or mutations that can lead to a new variant.

Viruses take advantage of these errors to boycott the immune system and become more infectious, but not necessarily to increase their pathogenicity. “Ómicron could go along this line: a virus that is better adapted to be transmitted but not so much to cause pathology”, Indicates the Spanish scientist.

But it is still too early to certify it, also to say that it will become a seasonal virus and the pandemic endemic with the presence of a more or less stable number of cases at a fixed time of the year.

“The data seem to indicate that omicron transmission is declining in South Africa, where it began to be monitored”, says Iborra, who adds that possibly behind this variant comes another. One possible evolution is that it becomes a virus for life, but it is still too early to tell. and also to mention that it is the beginning of the end of SARS-CoV-2.

VACCINES, LESS EFFICIENT

The mutations that the coronavirus has accumulated have facilitated, on the one hand, the infection and, on the other, that evade the activity of the neutralizing antibodies generated by the infection or by the vaccines, which also decay – it has been shown – over time.

Hence, insists Iborra, the need for the booster dose. Various studies, both preliminary and -some- published in Nature, point in this direction: monoclonal antibodies and vaccines – Pfizer / BioNTech, Moderna, Johnson & Johnson or AstraZeneca – are less efficient against omicron and a third dose could improve the neutralization of the variant.

But in addition to neutralizing antibodies, which could be boosted with a third dose, there is another arm of the immune response, T lymphocytes, which, although they do not recognize the virus, do identify the infected cells after which they begin to act.

T cells don’t seem to be as affected by omicron. In a preliminary study, researchers from the University of Cape Town (South Africa) found that in vaccinated with Pfizer and Johnson & Johnson this immune response was maintained by 70%.

The drop is much less than in the effectiveness of the antibodies; T cells are resisting omicron, Wendy Burgers said in a comment to Science, and this is consistent with all vaccines.

Salvador Iborra also mentions that vaccines continue to be very efficient to prevent serious disease, but, as was said from the beginning, those vaccinated can become infected and infect, that is why he insists on masks, prudence and social distancing.

But also in vaccinating the population of developing countries.

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