Omicron (SARS-CoV-2 B1.1.529)

Propagation speed

According to the WHO, the new strain is spreading faster than the previous ones. The data of Russian specialists also speak of a significantly higher spread rate. This may be due to the high rate of reproduction of the virus in the bronchi and epithelium of the nose and its ability to bypass the immune system.

The rapid spread of the omicron strain and an increase in the number of cases leads to an increase in the burden on the healthcare system and the risk of overloading it, and a decrease in the proportion of severe forms against the background of a growing number of infected actually leads to the fact that the absolute number of severe patients does not decrease or even grows. So, in a number of countries, for example, the USA, Israel and Denmark, the wave of infections with omicron has already caused a record number of hospitalizations.

Morbidity among children and youth

Children become infected with the omicron strain more often than in previous waves of morbidity, and more often require intensive care; young people get sick more often.

Omicron and other strains

According to virologist Sergei Alkhovsky, there is no absolute guarantee that the Omicron strain will displace Delta, since the Omicron strain is antigenically different from other strains.

Disease severity and mortality

As of December 24, 2021, the World Health Organization (WHO) assessed the severity of the disease in the omicron strain as lower or the same as in the delta strain. On December 28, 2021, the head of Rospotrebnadzor Anna Popova, based on data obtained in South Africa, stated that a severe course of the disease when infected with a new strain is observed only in unvaccinated individuals and those who are burdened with concomitant diseases - severe diabetes and severe oncological diseases.

Belgian virologist Marc Van Ranst, based on data available by the end of December 2021, said that young people are not affected or affected to a lesser extent by the new strain, but its impact on the elderly is still to be studied.

At the end of December 2021, the estimates published by the UK Health Security Agency (UKHSA)[en] became known, according to which those infected with the omicron strain are 50-70% less likely to go to the hospital compared to those infected with the delta strain , but researchers at Imperial College London have received lower estimates, according to which this risk is reduced by only 15-20%.

According to data obtained in South Africa by the National Institute of Infectious Diseases in South Africa and the University of Pretoria, mortality from the omicron strain has decreased by 75% compared to previous waves of COVID-19. The data were obtained by monitoring patients in a hospital in the urban district of Tswane (Gauteng province): among those admitted with this strain, 4.5% of the patients died, and before the proportion of deaths was 21.3%. In addition, those infected with the omicron strain were discharged from the hospital faster: on average, already four days after hospitalization, and pneumonia developed in only a third of patients.

On the other hand, early assessments of the virulence of the omicron strain are characterized by significant methodological shortcomings. It is necessary to separate the real decrease in the virulence of the virus from the effect of previous immunity: the omicron strain escapes the immune response better, which is why it is more likely to infect vaccinated and recovered patients, who are more likely to tolerate infection with this strain. Although researchers try to account for reinfections and the availability of vaccinations, a large proportion of reinfections may still go unnoticed. Thus, the authors of an early study from South Africa, which showed an 80% reduction in the risk of hospitalization after infection with omicron compared with the risk after infection with the delta strain, admitted that incomplete vaccination data and a large number of unnoticed reinfections do not fully account for the effect of prior immunity. The authors of the British analysis from the UKHSA also acknowledged that their adjustments cannot fully account for the impact of re-infections due to their underestimation. Data from Denmark, a country with a large population testing system and a low proportion of undetected COVID-19 cases, showed a 36% reduction in the risk of hospitalization due to the omicron strain compared to the risk of hospitalization due to the delta strain.

It is likely that both acquired immunity and reduced omicron virulence per se accont for the reduced risk of hospitalization in omicron-infected individuals. Reduced disease severity with omicron infection was also observed in laboratory animals, in addition, the study showed that omicron multiplied worse in human lungs than the original strain of SARS-CoV-2.

When infected with the omicron strain, according to the World Health Organization, the disease proceeds more easily or in the same way as when infected with the delta strain. However, the rapid spread of a new strain can lead to a high burden on the healthcare system, and the general risk caused by it is assessed by WHO as "very high". It can infect those who have been ill and vaccinated.

According to data at the end of December 2021, the delta strain was rapidly replacing in those countries where it began to spread. It is found in more than 100 countries around the world.

In Russia, as of January 20, 2022, the omicron strain accounted for 42.8% of the cases of COVID-19 detected in the country, and the delta strain accounted for 56.2%.

Omicron strain SARS-CoV-2 (SARS-CoV-2 Omicron, SARS-CoV-2 B.1.1.529) is a strain of the SARS-CoV-2 coronavirus, first identified in Botswana and the Republic of South Africa in November 2021, characterized by a large number of mutations in peplomeres.

When infected with the omicron strain, according to the World Health Organization, the disease proceeds more easily or in the same way as when infected with the delta strain. However, the rapid spread of a new strain can lead to a high burden on the healthcare system, and the general risk caused by it is assessed by WHO as "very high". It can infect those who have been ill and vaccinated.

According to data at the end of December 2021, the delta strain was rapidly replacing in those countries where it began to spread. It is found in more than 100 countries around the world.

In Russia, as of January 20, 2022, the omicron strain accounted for 42.8% of the cases of COVID-19 detected in the country, and the delta strain accounted for 56.2 %

Features

Strain SARS-CoV-2 B.1.1.529 is a descendant (representative of the line of generations) of B.1.1.

It is characterized by a large number of mutations in the spike (spike) protein, there are more than 30 of them: A67V, Δ69-70, T95I, G142D/Δ143-145, Δ211/L212I, ins214EPE, G339D, S371L, S373P, S375F, K417N, N440K, G446S, S477N, T478K, E484A, Q493K, G496S, Q498R, N501Y, Y505H, T547K, D614G, H655Y, N679K, P681H, N764K, D796Y, N856K, Q954H, N969K, and L981F, as well as the mutation ORF1b:T2163I, previously known by the delta subvariant AY, widespread in Europe.

Omicron strain has many unique features. Some of its mutations are similar to mutations of delta and beta strains, however, as of the end of November 2021, strains with intermediate mutations that usually occur during the evolution of the "wild" virus have not been previously identified. The absence of intermediate mutations of the virus in the population is unusual and turned out to be unexpected for virologists.

There are three main hypotheses explaining the appearance of a new strain.

Omicron strain SARS-CoV-2 (SARS-CoV-2 Omicron, SARS-CoV-2 B.1.1.529) is a strain of the SARS-CoV-2 coronavirus, first identified in Botswana and the Republic of South Africa in November 2021, characterized by a large number of mutations in peplomeres.

When infected with the omicron strain, according to the World Health Organization, the disease proceeds more easily or in the same way as when infected with the delta strain. However, the rapid spread of a new strain can lead to a high burden on the healthcare system, and the general risk caused by it is assessed by WHO as "very high". It can infect those who have been ill and vaccinated.

According to data at the end of December 2021, the delta strain was rapidly replacing in those countries where it began to spread. It is found in more than 100 countries around the world.

In Russia, as of January 20, 2022, the omicron strain accounted for 42.8% of the cases of COVID-19 detected in the country, and the delta strain accounted for 56.2 %