Ómicron 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 the SARS-CoV-2 like other coronaviruses? Do youThe pandemic is 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 Ómicron and other variants.
While some of the Omicron mutations had already been observed in Beta or Alpha, this is the first time the scientific community has seen them together. Since the end of November it was declared as worrying.
Of still unknown origin
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, what is clear is that the current coronavirus is not the same as the original and that accumulates multiple mutations in the spike that allow Ómicron to elude the immune response.
How much and why is it more contagious?
Is more contagious, more than 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 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; It seems that the way in which the coronavirus multiplies is now a little different.
Scientists from the University of Hong Kong concluded in ‘in vitro’ experiments that the variant prefers to multiply the cells of the bronchi rather than those of 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 covid-19.
Japanese researchers also conducted a study in this regard, also preliminary and this time in hamsters; found that Ómicron 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 Ómicron does not know how to do this so well.
They also analyzed the spread of Omicron and other variants: the former is between 3.05 and 5.57 times more transmissible than Delta (based on data from South Africa or the United Kingdom, respectively).
Do they all mutate?
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 decreasing 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 premature to know this and also to mention that it is the beginning of the end of SARS-CoV-2.
Less efficient vaccines
The mutations that the coronavirus has accumulated have facilitated the infection on the one hand and on the other hand, it avoids the activity of the neutralizing antibodies generated by infection or by 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 Ómicron and a third dose could improve 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 antibodies; T lymphocytes are resisting OmicronWendy 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.
More infections, but more hope
On the other hand, the variant is causing figures of daily infections that had not been seen in two years, close to a million global cases a day, although the World Health Organization (WHO) maintains the hope of ending the “acute phase” of the pandemic in the year that begins.
“I remain optimistic and believe that 2022 may be the year in which we not only end the acute phase of the pandemic, but also build the path to better health security, ”said WHO Director-General Tedros Adhanom Ghebreyesus, at a press conference.
From December 22 to 26 the barrier of 900,000 daily cases of covid-19 was broken, surpassing the previous record reached in April (894,000), while the Omicron variant, more contagious than the Delta, is becoming the dominant one in many countries.
But nevertheless, the number of global deaths remains in the current wave between 4,000 and 8,000 per day, figures that have not risen with the emergence of the new variant and that are similar to those of the last three months.
South Africa nurtures hope
Another figure that invites some hope is the fact that last week the cases in South Africa, the country where the Omicron variant was first detected, fell by around 30%, according to data from the latest WHO epidemiological report.
“We are confident that cases will decline in other countries as they have in South Africa,” said the WHO Director of Health Emergencies, Mike Ryan, who was also optimistic for the coming months, provided that it continues. the race for a more equal distribution of vaccines.
“It is difficult for the virus to be completely eliminated, but possibly shift to a lower level transmission pattern, causing occasional outbreaks in unvaccinated populations“Predicted the Irish expert. “We trust that this is the end, but certainly we are not there yet and there are still obstacles that we hope to overcome by achieving equality in the distribution of vaccines,” he added.
– Biden promises to accelerate the donation of vaccines to other countries before Ómicron
– FDA warns that rapid covid-19 tests may be less accurate with Omicron
– Long-term Covid: “I have to choose between walking and talking”